Ok, so, based on the discussion and my own basic reasoning, I have come up with a basic 20 yr timeline for this POD. Make suggestions where needed.
1518: Katherine of Aragon gives birth to a healthy girl that seems to be strong. A few hours after the birth, however, Katherine begins to bleed heavily and is dead by noon the following day. In memory of her mother the new princess is named Katherine and sent to Hatfield to be reared by her household. Distraught, Henry VIII mourns for his Queen deeply and makes grand statements of never loving another woman again. He also send his now pregnant mistress Elizabeth Blount off to the country to have his bastard.
1519: Thomas Wolsey bring the now adjusted King a list of brides that he could marry, including Isabella and Beatrice of Portugal, Renee of France, Catherine of Austria and Hedwig Jagiellon. While undecided at the moment, it was obvious that Isabella was a very attractive choice as she was reportedly very beautiful and very well dowered. In other news, Elizabeth Blount gives birth to a son that is named Henry Fitzroy.
1520: Henry VIII is seen at court with another young woman by the name of Mary Boleyn. One month later Lady Boleyn is safely married to William Carey. Three months later the affair seems to be over. Other than that, the possible brides of Hedwig Jagiellon and Catherine of Austria were cut from the list as the sketches that are brought to court are not to the Kings liking.
1521: The King finally officially proposes marriage to Isabella of Portugal as she is the best candidate out of the list given to him. The proposal is accepted and the court is madde ready for her arrival in the next year or so. A papal dispension is asked for and readily gotten.
1522: Isabella of Portugal is brought to England is regal splendor and is met with muted enthusiasm by the native peoples, who think she is very pretty but not the Queen Katherine they are used to. Henry VIII has the same reaction at first, but after a month announces that the Queen is the most 'beauteous person of looks and character'. When the royal children are brought to meet their stepmother, there is a sweet surprise when Princess Katherine runs to the Queen and yells "I now have a mother".
1523: Henry Fitzroy is brought to the court and given the title of Duke of Richmond. The young child is given many honours and the King is pleased that the Queen takes so easily to the child. There is much added rejoicing when the Queen is obviously pregnant. A minor scandal is caused when a young woman named Anne Boleyn is found to have been secretly betrothed to Henry Percy. After a tear-filled plea to the King and much support from the Queen, the young noblewoman is married at the King's expense to Lord Percy and they are given a manor in the North.
1524: Queen Isabella gives birth to a baby boy by the name of Henry who unfotunately lives only seventy days. But that is not the only misfortune too befall the royal family. Princess Mary is left without a fiance after the betrothal is broken by Charles V in favour of a secret betrothal and marriage to Renee of France, who comes with the promise of peace with France.
1525: With the betrothal between Charles V and Princess Mary broken, Henry VIII looks for a new betrothal for his duaghter. He sends initial proposals to Scotland and France. The year also culminates with a second pregnancy announcement by the Queen, which brings joy to the King. In addition to this, Lady Anne Percy (nee Boleyn) gives birth to her first and only child, a boy that is named George Percy.
1526: The pregnancy of Queen Isabella ends with a live baby girl that is named Elizabeth and sent to Hatfield, while a now very lively Princess Katherine is sent to a larger castle closer to London, like what has happened with her sister. Henry VIII recieves a very strong 'maybe' from France in terms of the betrothal between Princess Mary and one of the French Princes but there is an enthusiastic 'YES' from James V, who thinks that he could end up a ruler of all of Brittain. Charles V has his first child and son when Empress Renee gives birth to Infante Philip.
1527: Queen Isabella suffers a miscarriage. Princess Mary is officially betrothed to James V and the Prince Henri of France is betrothed to Princess Katherine. A betrothal between Princess Elizabeth and Infante Philip is broached. King Francis loses his wife when she takes to a disease and dies. Another Habsburg Infante is born to Charles V in the form of Infante Charles.
1528: Princess Mary is almost killed when the carriage she is in to get to court is accidentally set on fire with her inside it. She comes out with no burns visable and many count this as a miracle. Henry VIII sends a man named Thomas Henserson to the tower for this and everyone feels safer. As the anniversary of Queen Katherine's death draws closer, the Princesses Mary and Katherine are brought to court and go through many ceremonies that detail how much everyone misses Queen Katherine, which is quite uncomfortable for the living Queen Isabella.
1529: Queen Isabella is proud when, after almost seven years of trying she gives birth to a healthy son and heir, who is named Edward and given the title Prince of Wales immediately. In the wake of the Prince's birth, plans are made to immediately send the Princess Mary to Scotland to marry her betrothed husband James V. Charles V enjoys his first daughter's birth, a Infanta who is named Maria.
1530: Henry VIII has emotional farewell with his precious Mary, who leaves for Scotland on her 14th birthday. To console him, Queen Isabella gives birth to a baby boy that is named Henry and lives until Christmas, when he dies. Princess Katherine, meanwhile, is shocked when there is a proposal for her hand by none other than the aging King Francis, who has married his second son to Catherine de Medici and wants to have a young, pretty wife to compete with his sons young, not-so-pretty wife.
1531: Queen Isabella gives birth to a second daughter, who is named Margaret and sent to live with her sister at Hatfield. Henry VIII is sent the news that he is a Grandfather, to a beautiful baby girl that is named Katherine in honour of her dead Grandmother.
1532: Princess Katherine is sent to live with her new husband, the French King. While kind and caring towards his teenage bride, the King pushes for a 'full' relationship and the Princess seems to grow sadder everyday at court. Henry Percy dies of fod poisoning and Anne Percy (nee Boleyn) is left a wealthy, young widow. At the court she is approached by Charles Brandon, who thinks that the lonely widow will be an easy conquest. She is not.
1533: Henry VIII approaches Lady Anne Percy (nee Boleyn) to be one of his many mistresses. She pointedly says that she is not her sister and that it takes more than shiny gifts and worthless words. Henry VIII is hooked. Other than that, Queen Mary of Scotland gives birth to a son that is named James for his father. Queen Katherine of France gives birth to a daughter that is named Claude for the previous Queen of France. Charles V has another daughter by Empress Renee by the name of Eleanor.
1534: Lady Anne Percy (nee Boleyn) is given a set of apartments at court near the King's own, but there is no doubt that she is not doing anything inappropriate, as her sister-in-law is a every meeting between the two. Queen Isabella gives birth to her final child, a son that is named Henry, Duke of York. She dies after three weeks in confinment. Queen Mary of Scotland gives birth to a son named Alexander. Her daughter Katherine dies.
1535: Henry VIII approaches the Pope for dispension to marry Lady Anne Percy (nee Boleyn). Before the dispension comes through, Lady Anne Percy (nee Boleyn) dies from the Sweat, which ravages the country and also takes Princess Margaret.
1536: Henry VIII proposes to marry Princess Madeline, who is thrilled to marry the most handsome King in Christdom. Granted, the other main options are her Father and an aging man with an disproportinate jaw. The Pope is given a request for a dispension. Queen Katherine of France gives birth to a son named Louis. Prince Francis dies. Empress Renee gives birth to her final child, a daughter that is named Catherine
1537: Henry VIII awaits his bride to come to him and give him yet more heirs. In the mean time a young woman named Jane Seymour is his main mistress, later giving birth to a son named Edmund Fitzroy. She becomes a nun to pay penience for her sins.
1538: Henry VIII welcomes his third wife, the charming and delicate Madeline de Valois. She charms the court is proud when her daughter-in-law Queen Mary of Scotland names her lattest daughter Madeline in her honour. Princess Elizabeth is betrothed fully to Infante Philip. Henry Fitzroy dies of consumption.