problems

[alsur]

This is a modification of the monster creator, is legal I can do it?

[animatrix]

If you used another persons mesh, the going rule is an alteration of 30 percent or more of the entire base mesh, that is a quote from the people who make Poser software, but its defined in court by a judge if it goes that far.
But 50 percent or more would be better and if someone put an unaltered head on a diferent body, that would be considered copyrite infringment.