What you describe is called a conditional value list. The following tutorial describes two different ways to implement what you want. The first option is simpler to set up, but less flexible than the second option:
I do have a conditional value list already that allows me to choose the suppliers that are allocated to the product in question.
My question is that some of this suppliers are inactive and I dont want them showing on my custom value list, so even though they are allocated to the product beacuse they are inactive they should not show on the drop down.
Can you help?
You can either modify the relationship so that only "active" supplier records are related (Option 2) or you can define a calculation field in the supplier table that only returns a value when the radio button field = "Active" and refer to it in your value list definition (Option 1).
Define this relationship (option 2);
Orders::ProductID = Suppliers::ProductID AND
Orders::constActive = Suppliers::Status
constActive is a calculation field that simply returns the quoted text: "Active".
Status would be your radio button field where you designate a supplier as "active" or "inactive".