How to make PropertyGrid Collection Items semi editable?

How to make PropertyGrid Collection Items semi editable?

I have a class called "BasePath", which contains a drive-, path- and
metaname-property. Furthermore a have created a "BasePathCollection" to
show them in the propertygrid (expandable).
For adding a path you have to click the "three dots button", now you get
another propertygrid where you see all items of the "BasePathCollection"
on the left and the items properties on the right.
First all "BasePath"-properties were [ReadOnly(true)] and I could edit the
path by clicking to another "three dots button". But now I need to make
the the "metaname"-prperty editable and boom, suddenly I can't edit the
path. <-- The "three dots button" not not longer accessible.
What do I need to change for getting the "three dots button" back with the
ability to still edit the "metaname"-property.
Kind Regards
Mario
In a lack of reputation to post images I add a link with a image trying to
demonstrate the problem. Problem images