I think I still have issues in understanding yet would like to point out the issues with this theory
1) The saint married to Indrasena is from a much earlier time, because Ahalya is his grand daughter.
2) Since Nal can not be present in the Dwapar Yuga era, hence we might take Indrasena to be the daughter of someone from Nala's lineage, however there is no reason why they would give away their daughter for adoption especially since her brother was also adopted
3) Indrasena being Panchali's maid again isn't much of help here, why would she rename her maid to her previous name
What I could decipher of it is simply that she was somehow from the progeny of Maugdalya and Nal's daughter, maybe at some point someone Agniras family mighty have also been married into the family considering they were close.
Draupadi was intelligent and sharp, and hence started being compared to Indrasena in her knowledge and strength, hence was called her reincarnation.
Once Drupad adopted her, he wanted her to have royal etiquettes along with knowledge, so she was given a governoress, but why would she be called Indrasena
Remarriage isn't an option since in no way a girl who has already given birth resemble a Kumari Kanya