How old is your daughter and would the weight gain put her above a healthy weight!
Some pumpers do find that they increase their weight slightly when for the first 6 months or so, then it settles down, a lot of this is because their MDI control has been erratic had kept the weight down and the pump giving better control sorts of balances out the weight to a truer level!
She could be in a bit of a circle, if her weight has increased the fat levels could make her more insulin resistent so needs more insulin to keep control, and some of the weight could be if she's still having problems maintaining control with the pump then she could be feeding the insulin, both can lead to unnessary weight gain..
I would also check what type of foods she is eating, as the freedom of the pump, and the hearing the phrase 'Eat what you want' she may be taking too liturally, even with a pump you still have to eat within reason...
But I would get yourself a book called Pumping Insulin by John walsh (Knwon as the pumper bible) this will give you a lot of information about using the insulin pump, how to set good basal rates, how to work out insulin/carb ratio's and tackle many different situaltions with a pump, very usefull book for understanding how insulin pump therapy works.
Hopefully it may help you gleam some light to why your daughter is putting on weight etc, and see how you may tackle it all.