Yep. One pitcher and one position player. Anyone else and you have to make a corresponding move on the 26 man roster.
Which is totally doable for this team. After the deadline, there is no reason that Rosario, Gallo, Winker, Williams, Finnegan, Harvey, Floro, or Law to be on the 26 man roster, thus freeing up their spots for call ups.
Finnegan and Harvey (and Thomas) have another year of control. They aren't getting cut. They may get traded, but they are not getting cut after the trade deadline this year.