Hello, this is my first visit to the forum. I have been asked for the possibility of making Parquet tiles with 10 mm solid wood over 12 mm plywood with tongue and groove. Is this stable? Also, they will install it with 20 mm solid wood planks in the same rooms, also T&G. ths installation will be over plywood subflooring. How this could work?
Thanks.

Depends how do you intend to make your parquet

I'd say that a kiln dried oak glued with PVA or PU then clamped to the plywood would be very stable.

Is this panel then to be glued to the sub floor with the other boards meeting up, then the Parquet and the plank floor all sanded and finished on site?