Changing part of an element in the Master, is reflected in the child page,
so it’s not that they are unassociated.
I’ve had FWP tell me a change to the master has altered a child page -
though the child page shows no such change. I think it’s because the child
itself becomes untethered while existing master content is still connected
to content on the child. In 6, the Inspector has Use Master Content and Use
Master Settings not only for child items, but for the Page as well.
Check to see if your page inspector has them both options selected.
However, it only works when everything has been removed from the page. If I remove one element, then Reapply Master, that element is not restored. This is not the behaviour I recall from previous versions. So, perhaps it’s a bug.
I am having a lot of trouble with my Master & Page relationships. I have to re-check “Use Master Content” over and over, for example every time I change my CSS Menu item on the Master page. I’m thinking there is a bug as well.