I don't think giving Macedon to the Ptolemies would be a good idea, since it might mess the campaign up too much. Also I'm not sure about the Ptolemaic support since he was more or less kicked out of Egypt and was forbidden to come back.
RTR VII had them as rebels, which is a good way to portray their ''interim''- status. On the other hand, obviously it was a Macedonian kingdom at this time and nothing else, so perhaps they could be part of the Hellenic states? The obvious disadvantage this brings is, that Antigonos Gonatas would start at war with Epiros, Bactria, Cyrene and Pergamon as well. Epiros would be realistic, Pergamon is only one town and Bactria as well as Kyrene are abroad so it's not too bad. Maybe we can make a script that they conclude peace between each other (Antigonids and hellenic kingdoms) after Gonatas captures Pella?