That’s a nice question! I don’t really think they have godparents in Amestris as that is a Christian thing and Ed says it loud and clear he’s an atheist (even tho he beats the god of fma xD). But if they were to have them, the first kid’s (whom I’ve named Alan) godfather would naturally be Al, and as for godmother… um, I’d say Mei otherwise but she and Al probably aren’t officially together yet at that point (if I am to believe Arakawa’s timeline, Ed and Winry have their first kid when they are 19-20). But I’d kinda like to think they’d ask Izumi! Since she can’t have kids of her own, it would make her super happy that they give her such honor.

As for the girl (whom I’ve named Emma), there are several strong contenders (again Mei, Paninya, etc) but maaaaaybe Roy and Riza are going for the win. Ed is a bit reluctant when it comes to Roy at first but Winry tells him they can’t ask Riza if they don’t ask Roy as well so… he has to accept it (and secretly he thinks Roy deserves it).