The Heat confirmed on Wednesday that skipper James Hopes and wicketkeeper Chris Hartley had re-signed - and they will be joined by the Australian Test vice-captain, according to The Courier-Mail website.
Inaugural Heat captain Hopes signed a two year deal and Hartley one to join a Brisbane player list already boasting Dan Vettori, Alister McDermott, Nathan Hauritz, Dan Christian, Ryan Harris, Ben Cutting, Luke Pomersbach, Chris Lynn and Joe Burns.
Watson will reportedly also be on board after knocking back a Sydney Sixers deal.
The powerful allrounder did not play a game for the Sixers due to injury and it remains to be seen if he dons the Heat colours due to international duty if Brisbane have lured him.
The Heat said on Wednesday they would announce further signings during the recruiting window which concludes on Friday.
Each BBL team has to sign a minimum of 14 and a maximum of 18 players in the signing window.
Final squads will be completed by November 30.