We have two forms, a Members form with the members details which includes a field with their starting weight and a Class Register form where we select a member from the Members form and add their current weight. I want to add a field to the Class Register form that will give me the difference (loss/gain) from the starting weight on the Members form to the current weight on the Class Register form, for that particular member.

Can't seem to get my head around how to do this... is it possible? And if so can anyone point me in the right direction.

Many Thanks

Ian