There are not 2 ROAC groups. If you are talking of Gregory's synod of 1, then he is calling himself the "Genuine Orthodox Church of America" not ROAC. He only played that game for a short while.
I was aware of three, though things change so quickly with the old calendarists that my information might be out of date!
I was thinking of ROAC-L (Lourie), ROAC-G (Gregory), and ROAC-V (Valentine). It doesn't concern me what these people call themselves, but only where they got their formation or most authoritative standing (e.g., where they were consecrated or ordained). If you prefer, I could just call two of them "former ROAC" and still answer the original question in the exact same way.
As for ROCiE, the one in Russia that broke off is calling itself the TROC now, and I do not know if it is true, but there are stories saying the European ROCiE that broke off joined ROCOR-L.
Again, what they call themselves it not particularly important in answering the question. I can't keep up with the half dozen schisms or more in distant parts of the world. To me, they're all the same type of eggs in the same type of basket.
As for groups using the GOC name, there is the GOC of Chrysostomos II, the Matthewites and the Lamians. Since the Lamian left the GOC for the same reasons the HOCNA left the ROCOR, most do not count them as a GOC.
Well, in the case of the GOC I only listed one, and left the rest to a vague, other "old calendarists" grouping. But there must be a half dozen (if not a dozen) Greek Old Calendarists, none of which are in communion with anyone else.
As for the ROCOR, I seem to recall you contacting the Serbian Metropolitan in America and he said there was no communion between the SOC and ROCOR? That situation was always very vague
Well it's odd to hear someone in ROAC arguing against ROCOR communing with the Serbs. That's a new one on me!
It was vague, admittedly, and probably purposely so (you can thank the revered ROCOR hierarchs of years gone by for that vagueness... Laurus tricks people, Philaret just politically maneuvers I guess). In any case, ROCOR said quite explicitly in 2000 or 2001 that they were in communion with Serbia, and the Serbs have concelebrated here in America with ROCOR a few times since then. The bishop was wrong if he didn't think the SOC was in communion with the ROCOR -- it wouldn't be the first time a bishop was wrong, Chrysostom said that the majority of bishops are wrong and in for a world of hurt on judgment day (Homily 3 on Acts).