I have been made product leader for a big international customer, designing a physical product for them that will have to perform action A, B and C. But seeing as the needs of the customer will change and we wish to include other functionality the design needs to be flexible.
Now, my German colleagues have completed a design that does A, B and C and some additional features that were not asked for but that are really handy and nifty. They presented this to the client as a part of the joint-development-agreement. They claim that the design is complete and all that is needed is some finishing touches. The problem is that after studying their design I have found a number of weak design elements and decisions that basically will lock us in one design path that may not be optimal. The weak elements are easily corrected, the wrong design path is not.
I have had my fill of monumental Charlie Foxtrots when it comes to inheriting a design and I am not keen on doing it again. I told them that changes may be needed on the design but they become defensive whenever and regardless how I voice my concerns. I believe they have invested their pride in the project for better or worse.
I have discussed the matter with the team's superior and we are in agreement, but the team does not see it this way. I could pull rank on this issue, but for obvious reasons I don't want to spoil a good working relation, we will work together again in the future and it would be nice not to have an ongoing grudge.
How do I scrap the design without spoiling the relation?
Is it even possible?
In light of some of the comments that have been coming in I believe some clarifications are in order. The product will be a cast product, any errors introduced today will stick with the product for at least 5 to 10 years before any revisions can be made. That means that I will be held responsible for any and all errors in the cast that pop up during these 5-10 years without having a reasonable chance of correcting them.
It is ludicrously expensive to change cast molds.