Sankyo... I'll get back to you on sankyo.
Control can be palm to palm if there is a direct connection to uke's center. The other hand can support by resting on the back of uke's hand, so it looks a bit like a hand sandwich. On the takedown, the back hand ends up in almost a reverse yonkyo grip while the hand that initially had control through the palm slides up to the elbow. So, yes, it's possible.