So you don't care if you don't meet this requirement?

If both are present I want the 5V to come from the regulated source.

 

Hello,

With the two diode setup, the source with the highest voltage will be used.

Bertus

 

Yes, it's not that important a requirement.

 

Yes, it's not that important a requirement.

Well, if we had known that earlier we could have saved a lot of posts.

 

Then the solution is simple. Use one 1N5817 diode and one 1N4001 diode.
The source connected to the 1N5817 diode will take have first priority in delivering the power.