Well, It should be tight but some of the best times I have had were on cruises with 4 girls in a cabin. One thing I recommend is that some ppl go up to the spa for their showers. The showers are nicer and you can go up the elevators in your robes and back down in your robes. No big deal. You are all family so it should be fine. What lucky girls I hope they appreciate it. Have a great time and remeber if it gets a little crowded youll laugh about it later.