Fred & George are likely in the Order as you can guess, probably the same with Lee Jordan since they're all like brothers. Spinnet wouldn't join without Johnson like we said before, they're inseparable.
The others are negatives. Francine hates the Order, she always has, and she's a terrible actress as you can tell. Percy Weasley is committed to the Ministry above all else. Fergus Plunkett is too [...] Fergus to get an invite, I'm sure. I don't know about the older Weasleys, I didn't spend much if any time with them. It wouldn't surprise me, though.