Not only am I here to make theory's but to disprove theory's, and I'm sorry to all of you how love this theory, just remember, this is just a theory, nothing is proven.

First hint: One starting Licita, she was 26 at the time of death, and she told Liebe that her son would be about his age now, Liebe looked around 6 years old meaning Licita would have been 20 when she had Asta. Now there's no saying how old Allen would be when if he never died, but he dead when he was only 17. 

Second hint: Now tell me when did this 17 year old boy have enough time to go all the way past the strong magic region to the clover kingdom and hook up with a 20 year old women and make a child? Also, let say Allen did go to clover and meet Licita, he would have dead, because her body steals life mana from any living force around her, which would have included Allen, it's not like his that magical.

Third hint: Okay so people are guessing the Zenon and the rest of the dark triad are somewhere in there 30, meaning that if I did the math right Licita would have only been like ten when Allen died. So yeah.