How to structure 2-3 property deal

[Jeff G.]

I was originally going to do a cash deal to seller (private mortgage from family member) for a property through a Realtor.  Then I found out the seller has several property's and is selling them one at a time.  I am very close to convincing the seller to let me preview all the properties and put together a deal for 2-3 of them with conventional mortgages.  The plan is to have the person who was willing to put up the cash for the first property put forth what will be the same amount but use the money for the down payments on 2-3 propertys instead of the cash purchase on the one.  I'm guessing I would need to form some kind of legal partnership to get the loans to go through.... 

I have a mortgage on my primary residence and one other investment property currently (with a private mortgage to the same family member)  

My thought was to pay back the 35-40K to my family member on a 5 year note like a car loan at 6-8% which they agree to. This will still leave manageable cash flow on the properties.

My concern is the banking side.  Would a blanket loan be an option, or Three separate traditional mortgages?  OR??.....

Sorry if this is a bit rambling.  But any insight?

Thanks,

Jeff