Why only Charlotte and Madeleine? What about Louise?
In any case, we already talked about this question here:
Charlotte was the second child of Francis and Claude, who died young. What if she hadn't died young?
www.alternatehistory.com
We had come to the conclusion that Charlotte would likely marry James V. Likely, they would have a son who would be raised in Scotland, would be Catholic and would have good chances to manage to prevent the rise of Protestantism in Scotland.
As for Madeleine, it is more uncertain. I had suggested a Portuguese marriage (maybe with Luis, Duke of Beja) which may prevent the end of the Aviz and the Iberian Union. However, it was only wild speculation and I don't know how likely it is.
The Duke of Lorraine? You mean Francis I of Lorraine? Why wouldn't he marry Christina of Denmark as in OTL?
As for Antoine, I don't know.
Antoine was next in line after the Valois (but he was not First Prince of the Blood as this title did not exist yet and was invented by Henry IV) but it was not that important at this time as there was little to no reason to imagine male Valois would die out.
Even with Jeanne d'Albret, her parents thought Antoine was not important enough for her. (It is true that Jeanne was the heiress of a throne in her own right but said throne was associated only to a very small portion of realm, the essential part of Navarre having already been conquered by Spain and, even for keeping this small portion, the kings of Navarre were dependant on the kings of France.)
I don't see how a marriage to Antoine may help the Valois' policy and alliances.
If Antoine marries Madeleine anyway and has children with her, said children would be raised as Catholics and the succession crisis after Henry III would be avoided. Of course, butterflies are likely to save the male Valois anyway.
Marguerite had been promised to the future Philip II but this engagement was broken when war restarted between their fathers.
She had also been considered for Henry VIII after Jane Seymour's death.