I bought my game from Big Fish but now I want to buy it from LDW do I have anything to know before I download the LDW Version
Ex Do I buy from Ldw com or virtual families com
Ex what do I delete regarding Virtual families first
Ex can my files be transferred from Big fish to Ldw

Update: I bought from ldw.com
I delted the folder in documents and uninstalled from big fish
I made backups of my original families and I am still wondering whether big fish files are comptable with the LDW Version.

Were the savegame files in an LDW folder or a BFG folder?

Since you were able to access them in order to back them up, there should be no difficulty. Keeping a copy in the backup folder, make certain the savegame files are in the following folder location:

C:\\My Documents\LDW\Virtual Families 2: Our Dream House

That is where the game will look for the files.

I decided to start over my families but keep the backups of my old families. And it is kinda fun starting VF over. Because I was sad that I had almost reached the 30th generation (I didn't want to see Cyber and Jessania leave the family tree)

ISTR that BFG hadn't bothered to update their version of VF to include the bugfix for the 30th generation anyway. You probably wouldn't have been able to continue with their version anyway!

Actually they did, they have 1.00.09.
They got it in September 2010.