If they can sit unassisted for like 10 seconds, does that count? Or do they have to be completely stable.

DS is doing that tripod support when he is crawling into a sit position so he's more stable than DD. DD is not crawling yet but can sit for about 10-30 seconds, if I put her into a sitting position. She's stable but not stable... if that makes sense. She does not do that tripod yet. She does arch her back and that will bring her out of a sit position so I can't leave her unattended.

I just always wondered what the unassisted sitting meant to others.