"Fusion" of two objects

 From:  Rudy
580.1 
Rudy here.
it's me again.

How do I fuse (merge), the two objects in question?.
See attachment.
Actually mi ideal is that the fusion is seamless (is is the right word?...English is my second language) with no hard edges in the point of fusion between the two objects.

Any suggestions welcome.
Thank you.

Rudy