While Peukestas may have sons, they did not appear at all in the sources ITTL, either because they were irrelevant, or more likely too young to have played apart. The sources are heavily biased towards what I'm calling the legitimist faction now (so I dont have to say Alexander, Eumenes, and Perdikkas all the time) so far as detail goes, since the main sources ITTL are Eumenes and Hieronymous of Cardia (also an OTL source used extensively by Diodorus). So the record for Peukestas's reign is somewhat lacking.
Marrying his daughter to his nephew actually makes sense. I hadn't thought of that but that would be a sensible match to legitimize Alexander Neos's position.