What counts as "expanding family size" for a second FHA loan?

[Ellie Narie]

Does the number of tax dependents have to increase? What if you don't claim some of them but they're still your legal dependents? 

What if your kids just get bigger and you need an extra bedroom so that they don't share a room anymore? Would this count? What about adding a live-in nanny or au pair to the household who needs their own bedroom? 

If any of the above count, is it possible to get another multi-family property, where at least one unit has more bedrooms than your previous multi-family apartment? Such as, let's say you have an FHA fourplex where each unit is 2 bedrooms. You want to get another fourplex where at least one unit has 3 bedrooms.