Ok, how about this scenario: The death of the Queen of England, Catherine of Braganza, in 1663 was due to illness. The dying Queen herself believed that, during the last days of her sickness, she had given birth to an heir and begged to be allowed to hold her "son". Charles II of England, unable to be the one to tell his bride the truth, would instead bring his newborn son by his mistress Barbara Palmer, who fussed that her son would die in the arms of the Queen, which did not come to be. Instead, the baby comforted the dying woman, and it was on the 2nd of Novemeber, 1663 that Charles II of England was officially a widower and thus available for remarriage.
It was rumoured that, in the wake of his new state, the King planned to remarry to a distant cousin, Frances Stuart. A dim but beautiful woman, he had unsuccessfully attempted to take her as a mistress previously, and with their growing closeness in the immediate aftermath of the Queen's death, many feared that they had already become betrothed, if not fully wedded. They would be quite close by Christmas and in France, the note of congratulations for his marriage was prepared to be released the moment Charles II of England announced they had wed. This, however, seems to have been premature, as it turned out to be based merely on rumours. Instead, the King began negotiations for a new bride.
His first choice would be Élisabeth Marguerite d'Orléans, cousin of the King of France and an enchanting young woman in her own right. However during the early negotiations, a contender of the King's bride came in the form of Margaret Theresa of Spain, the heiress of Spain after her deformed brother. While the French match offered a rich dowry and a good, solid alliance with a traditionally antagonistic France, the Spanish match offered the potential of the Spanish Empire. The temptation of Spain proved too much for the King of England and in 1664 the 13 year old Infanta of Spain was betrothed to the King of England, to arrive in England when she was 14 and to begin the proper consummation of the union when she was 15.
Arriving in 1665, the Infanta of Spain delighted her new husband, who promptly designated the title of "Petite Douceur" (Little Sweetness) to his new Queen, a pet name that the Infanta would retain with her husband until her death. The cohabitation would, of course, wait until the Queen's 15th birthday. However, the two would grow close during this time and eventually the Queen of England would be comfortable enough to give her husband his own pet name, entitling him "Mon roi géant doux" (My Gentle, Giant King), after his height in comparison to her own shorter stature.
Their first child, a daughter, was born in January of 1668, named the Princess Sophia Stuart. With her daughter, the Spanish Queen found herself quite proud, and it was then that the teenager attempted to send her rival, Barbara Palmer, away from the court. Ultimately a fruitless attempt, the Queen would settle for the King simply removing his mistress from his wife's attendance for a time, instead placing her in a position that allowed her less access to the Queen.
A second daughter would be born in 1669, the Princess Margaret. Unfortunately, the Princess Margaret would die mere days after her birth and the Queen would meet the tragedy with sadness, falling into a melancholy state throughout the rest of the year. However, this was alleviated by her third pregnancy in 1671. Having just entered her 20's, the Queen of England was beginning to find her confidence as a young woman. An early victory against Barbra Palmer would lead to her opposing several of the women her husband would enjoy on the side and bets went around the court, seeing if the Queen would "domesticate" her husband. However, all this came to naught after the pregnancy of the Queen of England came to an end in December of 1671. Giving birth to a healthy son, named Charles after the King, the Queen of England died as a result of an emergency Cesarean Procedure, performed at her instruction. The King was truly devastated.
Having lost a second bride, the King of England was not immediately agreeable to a third marriage. Having now given England a male heir, the King felt he might be able to live a single lifestyle, at least for a time. However, fearing the Prince of Wales might grow sickly, and the Princess Royal would be all that was left, the King of England began negotiations with France for a new bride. In an odd moment of coincidence, the same her he had lost his bride, his former potential Queen, Élisabeth Marguerite d'Orléans, had been widowed by the Duke of Guise. The mother of a young son, the Dowager Duchess was somewhat antagonistic to the match, until the death of her child in 1673. Thus, in her grief, she agreed to marry the King of England as a way of escaping France and all it's memories of her son.
With his third bride, the King of England would find himself less emotionally attached than previous unions. While pet names had been the norm with his previous Queens, with Élisabeth Marguerite d'Orléans he would keep a formal tone to their correspondence. While this would obviously soften with the birth of their children, it was not for naught that many joked that the King was more married to Nell Gwyn than the Queen herself. Despite this, the Queen would be the mother to a further three of the King's children.
The first of the royal children would be the Duke of Clarence, the Prince Henry Stuart. Born in 1676, on his mother's 30th birthday, this son represented the softening of the previously stiffly formal Queen, who would grow more popular in the court after this time. A second son in 1679, named James and given the title Duke of Kintyre, would follow and the final birth of a Princess in 1681, named Henrietta after the Duchess of Orleans, who had died in 1670.
Now this is is the new royal family:
Charles II of England (b.1630: d.1685) m. Catherine of Braganza (b.1638: d.1663) (a), Margaret Theresa of Spain (b.1651: d.1671) (b), Élisabeth Marguerite d'Orléans (b.1646: d.1696) (c)
1b) Sophia Stuart, Princess Royal (b.1668)
2b) Margaret Stuart (b.1669: d.1669)
3b) Charles Stuart, Prince of Wales (b.1671)
4c) Henry Stuart, Duke of Clarence (b.1676)
5c) James Stuart, Duke of Kintyre (b.1679)
6c) Henrietta Stuart (b.1681)