Single Trip Insurance for Family with different return date

MyRealNameToo

As previously said, it's not likely to come up in questioning as your claim is for medical expenses rather than anything else. 

Certainly if it was an annual policy there'd be no problems as with the text quoted earlier it covers you travelling together and independently. A single trip may be a touch more risky that they will argue it's not what was intended but if that will hold water with the ombudsman is another matter. 

Did you price an annual policy at the same time? Often there is little difference than a single trip one and it gives more flexibility. If it's a long trip an annual policy may even be cheaper than a single trip.