Changing and/or adding rooms within 8 wks of sailing

[TwinsXTwo]

There are 5 of us traveling as a family.  The most economical is 1 OV.  If I book the 5 person OV now and prices drop, can I add a room and change occupancy of the one room from 5 people to 3 and add a second room with 2 people?  (without major penalty?) We are sailing on the 3/4th passenger free if I book now...

Just can't wrap my head around what to do.  If I go for the 5 person OV, am I "stuck"?

[keep on cruisin]

You should check with NCL what the cancellation fee would be for the 2 free.  If prior to final payment there would be no fee.