Correção de frase "My house has two rooms, all of them...''

My house has two rooms, all of them have TVs.

A forma acima está correta.

Ok. Mas porque usamos o have neste caso e não there is? Tem alguma regra?

1. Onde você não deve utilizar “have”. Use o “there to be’’ (there is ou there are) para dizer “tem”, quando equivaler a “haver”, “existir”.

2. Onde você deve usar “have” ou “has” (com he, she, it) e não usar “there is” nem “there are”. Quando ‘’ter’’ expressar a ideia de posse, use have e não “there is” nem “there are’’.

Cf. "There is/There are" x "Have/Has": Como utilizar

Bons estudos.

My house has two rooms = dá sentido de posse e a casa não pode ser dona de algo. Como fica isso?
All of them have TVs. = aqui tbm tem sentido de posse e have é só para posse. Como posso entender esta frase?

My house has two rooms, my car has four doors and my cats have legs (and like dogs they are digitigrades).
The house having no possessions thing, okay, but let´s make another analogy then. If some have a cold, is it a possession? No.

Have is not only about possession, it can be auxiliary verb, it may be used to make a (fixed) expression (having a drink). They had a fight - no possession here, they just "brigaram".

Same goes to the subsequent part of the sentence: "...all of them have TVs to watch." (I tinkered with the text).
All of them have TV sets. So, who or what have those TVs? The rooms.