Good day.
I created a DB for a friends garage using a main form Customer Details, (1) a sub form  to record Customer Vehicles (2) sub form to record which vehicle needs repairs (3) sub form to record parts and cost of material used.
The main form and 3 sub forms need to be linked. I have the main form and 1 and 2 sub forms linked ok but can not link the #3 sub form.
I need help with the relationships as I have tried always to get it right but failed. Its driving me crazy.
I would greatly appreciate if someone could help me.