The way the bidding has been described I would bid 4 ♠ and certainly not 3♦. And if indeed 3D is a help seeking suit bid then I, personally,shall bid 4♠.
Trial bids Reaching Game
#22
Posted 2020-September-29, 12:43
After not opening the bidding with 1♠, it wouldn't occur to me to bid anything other than 4♠. If I was taking over for somebody who had an emergency and had to leave after bidding 3♦, if partner didn't accept the invitation and signed off in 3♠, I would bid 4♠ unless partner tanked and effectively barred me from raising.