currently running solidworks 2016

I work frequently with multi-body parts - example to make one of my parts we start with a forging part level, then a semi-finish part level and finally a finish part level. each of these levels is its own standalone model/part #

• Part 01 - forging -I model it then , I insert custom properties such as Part #, Description, Material
• for Part 02 - semi-finish I insert Part 01 to start with only bringing in the solidbody. Then model in the features. I insert custom properties such as Part #, Description, Material
• for Part 03 - Finish , I insert Part 02 to start with only bringing in the solidbody. Then model in the features. I insert custom properties such as Part #, Description, Material

now for example - when I go to open say just part 02, I notice in the background solidworks also opens part 01, not sure why. Then when I go into the custom properties for part 02 I notice the information that was in there for part description, part number and material is missing......?

what is causing this to occur. This issue is only happening when I am working with multibody parts.