Plural Possessives with Separate Ownership

Hello, Time-axis, and welcome to the Grammar Exchange.

@time-axis posted:

Let's say there is a group of knights called the "Knights of England", which we can abbreviate as "the Knights" if we want to.  Each of these knights has their own bloodline.  They are not related.  If I wanted to refer to these bloodlines, which of the following would be correct?
A. The Knights' Bloodline

B. The Knights' Bloodlines

C. The bloodline of the Knights

D. The bloodlines of the Knights

Would the context that there are a great many knights and they are very unlikely to share the same bloodline have any bearing on whether answers A or C are correct?

My understanding is that only B and D would be valid.  Is my understanding correct, or are all of them valid?

Yes, only (B) and (D) work with that meaning. If you are worried that people might think each knight has more than one bloodline, you can use "respective," "individual," "various," or "several" to reduce the likelihood of that reading:

• the Knights' respective/individual/various/several bloodlines
• the respective/individual/various/several bloodlines of the Knights