Sounds a little bit worry.
1. You can't merge collections of different accounts by your self.
2. You can install vghd (for 1 specific online account) on two different machines. After that you have to contact customer support to reset the counter. E.g. if you bought a new machine etc.
3. To get solved your Problems you have to contact customer support in any case.
I'll point Celiné (CS) on this thread but you can also use the Help section .... for the "too many installs" problem you have to go here:
http://www75.virtuagirl.com/csIndex.php?csCatId=13choose "I received an error message stating 'too many installs'" and fill in the online form.