Creo Challenge for fun 2017

Sounds like you need to join the multi-body (Focus Group for Embedded Component Use Cases in Creo‌) working group!  There were lots of discussions in Boston last month on the best way to handle this very concept.

It's a 20+ year old problem. I would be surprised if many use-cases and solutions haven't been kicked around inside PTC development for a long time. The problem is significantly complicated by dealing with any PDM system.

I don't get it...

Dimensions on a part should go on the drawing of a part.

If later those key-lock inserts need to be added, then you create an assembly, insert the first part and place/constrain the key-lock inserts. The drawing of the assembly only shows the dimensions regarding the position of the key-lock inserts...NOT any dimensions of the part (which are all at the drawing of the part).

Key-lock insert installation is considered an inseparable assembly, which is detailed as a part. Same thing with weld-studs, PEM nuts, and others.

Not everyone treats them this way, but plenty of users do.

I agree that the resulting assembly will be inseparable, but I will have to disagree for the need to detail that as a single part/component.

In our case, person A can make the main component and person B can buy/purchase the key lock inserts. Then, person C receives all the components and assembles them.

Person A needs to have the drawing of the main component, nothing else. Person C only needs to know where those inserts need to be place (location, depth, etc.), but he does not need to know how to produce/manufacture the main component.

That being said, at my previous job I did use the "single-part assembly" method, but that was for sheetmetal (but I can't remember exactly WHY)

Many companies want to buy those sheetmetal parts complete with the PEMs or riv-nuts, etc installed. They consider it an added expense to produce the "extra" drawings, track the multiple part numbers and/or setup operations to add the components in house after receiving the sheetmetal part.

From an creo standpoint, it used to be significantly difficult to replace a part with an assembly. Interchange assembly was your only real option if you had any parent child relationships to speak of. It's easier now but depending on how you build your models, it can be a mess.

It's really a company-by-company decision. We tend to want our software to be flexible enough to help us do our job and not make impossible to adjust to situations and changes as they come up.

My proposal for the Creo 4 view replace model project included replacing a view of a solid with a view of an assembly with the solid as an immediate component.  But as it went, that's on the 'for the future' list.

Inseparable assembly or separable assembly, the file is still an assembly. Even with Unigraphics, which allowed multiple solid bodies in a single file, we used the assembly approach for the addition of PEM fasteners, weld studs, etc.

Solidworks Model Mania Challenge from 2010.  the Original and Revised drawings of the 2017 Battle Royale look eerily similar to the Phase 1 and Phase 2 models from the 2010 challenge in SW.