Make the two match fields in your relationship fileds of type text instead of number.
Thanks that works as you suggested but there is complication which I didn't mention. Later this field is used to order so it has to be in number format as ordering numbers listed as text doesn't work to well. I realise that all fields should be text unless you want numbers for a reason e.g. calculations or ordering.
FM is new to me as all my database work has been in Access so I am on a steep leaning curve as FM is somewhat different.
You can add a calculation field for your number format.
Simply put the name of this field in the specify calculation box and specify Number as the return type. Use that for specifying your sort order. (You don't have to place this field on your layout anywhere, just update your sorts to refer to it instead of the original, now text field.)
From a design stand point, you may want to modify things so that the non-numeric text is in one field and the number is in another. A Calculation field or just two layout merge fields side by side can be used to display the numbers in text in combination.
Even in Access, I'd keep the numbers and text in separate fields.
Thanks for that just what I wanted. Don't go away I will almost certainly be back for more.