External References when trying to open - read only

[Karpinchick]

I have a file named 'Master' and within it are the layouts with the titleblock as well as the drawings: Floor Plan and Elevations. 

If I have the Master open and try to open the Floor Plan, it opens as a read only - which is frustrating because it should not. But if I close the Master file it opens perfectly fine.

Now if I have the Floor Plan open (without the master file opened) and I try to open the Elevations I get this error:

"File (file location path)\File Name of Floor Plan.dwg is open for editing. 

Unable to demand load it. Performing a full read instead. "

What does that mean?
If I press OK it still opens and I can save, but it does not update in the Floor Plan drawing until I close the file and manually update it. 

Why is AutoCAD doing this. I use to be able to have all of them open and it updates through-out. 

This is extremely frustrating and inefficient for my work. 

Please someone help.

Thank-you.

[M_Hensley]

In Options on the Open and Save tab there is a setting for Demand load Xrefs. I believe Enabled with copy is the one that lets you open and work on the xrefs while having the drawing they are referenced in open also.