You need to do this to comply with federal tax law.

Z and RESPA and must comply with the TRID rule.

There are very good reasons why most carriers prohibit the exercise which typically leads to a frustrated tenant as he seeks to comply with the requirement.

Section 8 tenants have an incentive to comply to the rules. 

I have been sending a reminder text to her on the 1st and she has been complying. 

In addition, I don't understand why she believes it's not her responsibility to follow up with the Seller to make sure the requirement is complied with. 

I am due to close on a rental property next week but have yet to see the lease the tenants have signed with the seller and now I have to comply with.

The simple answer, I imagine, is to serve them a notice to comply and require the additional deposit or the removal of the pet. however they are the best tenants I've had in my investment career (4 years), moreover evictions are temporarily on hold till who knows when so my threat to evict can be drawn out dramatically longer.

Give them a heads up before doing treatment with what the pest guy says needs to be done,, trash, put food items in plastic containers,, ect.If they don't comply give them notice to move, non- compliance with terms of lease, cleanliness. this could infest your entire building, and I would have pest guy treat all neighboring apartments. 

If you do not comply it is a $100 fine each time, but may escalate with each additional fine.