I don’t think Trump and Cruz can pull their tallies together at the convention; their individual delegates are pledged for the first ballot. On a second ballot, I guess they could.
Rep Establishment has the much weaker hand.
Cruz can release his delegates, and then they aren’t bound to anyone. Most will be establishment players who were granted the position of delegates from the State parties, but if Trump is less than 200 away from an outright win, I would say the odds are almost 100% that he would get enough votes if Cruz released his delegates.