Themyscira'd be a nice safe-ish place for your daughter to hang out and wait for you to get resurrected.
Hahahaha not so much. Themyscira gets sacked about twice a crossover.
That said, while that *should* be a good idea in theory and I can't think of a character who'd be a better choice for mother than Donna Troy, I'm not sure, and I say this with love, that Roy actually has contingency plans for Lian on that level in the event of his death. That he adores Lian, does his best for her, would do anything for her, is not in question, but nevertheless, he has never really been the world's most responsible parent (a flaw he comes by honestly, it must be said).