Financial question about rental purchas

[Steve S.]

I a friend who has agreed to terms on a prospective rental with a colleague for $100,000.

After securing funding, etc it became clear the property was worth more than the seller (someone i have known forever) thought and they would like another $30,000 for the property.

Their numbers all work out at $130,000 so they are fine with paying that, but I am not sure how they make this happen from a documentation, tax, etc perspective.  

Any thoughts on what issues this would cause and how to go about making sure all i's are dotted?

[Mags S.]

to make the new sales price of $130k part of the existing agreement, write up an addendum or change to existing contract - something like, buyer and seller agree on a new sales price of....  It should be signed and dated by all parties. It should be included with the original sales contract. The new sales price may impact loan amounts, tax transfers, etc. - anything the old sales price affected.

Added:  did you settle on this property already?