Well, it's been a long, long time but it's better to comment on it now than never.
I'm in agreement with JamesYTP, I never really thought to look at it in this context in terms of reproduction. Your analysis supports it by having Father react to Edward Brothers, becoming rather curious of their existence. In fact, the fact that he was referred as father, hinted at the possible curiosity of furthering his own legends, but because of the circumstances, it's was an impossible feat.
Does the original FMA anime has any hints on the topic of fertility and reproduction? I know that it had an anime exclusive Homunculus, the son of the teacher and the Edward Brothers' mother, which I thought spring up another connection with naturalization. Despite being brought into the world through the trials of alchemy, the two bonded somewhat in a mother-son relationship, as her mother instinct kicked in.