You could also use:
I will pay for both your trips and stays.
But both of them could be used.
1-I'll pay for the trips and stays of all of you.
2-I'll pay for all your trips and stays.
Is 1 correct?
Could 2 be used instead of 1?
You could also use:
I will pay for both your trips and stays.
But both of them could be used.