@Chella17 whilst I don't understand how you fit 10 people into two bedrooms but you could do the following
Listing A = 1 bedroom in a shared house
Listing B = 1 bedroom in a shared house
Listing C = 2 bedrooms in a whole villa
Link the calendars as follows
Listing A to C
Listing B to C
So if A or B book C disappears
If C books A and B disappear