Honoring an existing lease

[Shawn Root]

So, if you purchase a multi-family property and one of the tenants has been getting a discount (written into the lease) to do yard work for that property as well as another one that the seller owned, how can you continue to honor that in the lease?  He won't be able to fulfill his portion of the terms (that were too generous to begin with) because the other property has been sold to a different buyer.  You obviously don't want to give him a discount for work he's not performing for you.  What do you do?

I've read that we must honor the existing lease, but some of the stuff in the lease just isn't valid any more.  For example, there is info in there about whom to pay.  That is changing, obviously.  How much of the existing lease are you responsible for continuing?

I'm in Texas if that matters.