Example 1) Ford calls and asks us to change the gating for a particular pattern that they use to produce crankshafts. They tell us where to move the gating, we just do what they request. We may or may not be asked to provide an updated drawing for them. If so we have our detailer make a hand drawing or an Autocad drawing from a sketch that we make of the changes.
Example 2) Ford asks us to make a new 3.8 L cylinder block core box. Again, they tell us what to do. They either send us the prints (oops, that’s a joke, we’re talking about Ford here, aren’t we?) or they reference a previous print and tell us to make it like that with so and so changes. They send their CAD data to our designer (subcontracted), he creates a tool cutter path and sends it to us for any CNC machining. We make it according to their specifications. Afterwards they may ask for a drawing and we have our detailer make a hand drawing or an Autocad drawing for them.
In both of these examples we do not make any design decisions. IMHO we still must have FMEAs, control plans and R&M planning (we’re TE) but we are not considered design responsible.
In the beginning...Ford supplied them and still have ownership. But they have been modified so much over the years there is little resemblence to the originals. We just change this and that, according to their whims (gating size, screen locations, etc.), and then add it to their drawing(s). They actually do not have any updated copies. If our facility burned down... !
You did not design the 3.8L cylinder block box, so you do not own the design. Therefore you are not design responsible. The standard question is who designed the product. The other standard question is whose name is one the drawing - the drawing from which the cost estimate was made.
Generally speaking, companies that are design responsible want to create something that does not exist now, and study the market to see if and how successfully it will sell. Then they draw / design it and verify the design, then market it.
I think in this case you are just being a good supplier, by granting your customer's wishes.
I think though you may want to look at your document control?
A related question would be regarding the process of manufacturing the pattern. Though Ford supplies the data and drawings. They do not tell us how to actually process the job. Would we not be responsible for designing the manufacturing process? Or is this covered by FMEAs, Control Plans and R&M planning?