yes create the addendum but realize the tenant who has been paying could ask to be reimbursed for these costs as well as not accept the addendum.

I'll subto his existing mortgage and pay off the 120k.

You will pay them and everything will then fall apart.

I am just starting out with a STR and found that VRBO is not very specific if they are collecting the tax and paying it to the State as a marketplace facilitator or am I responsible for this tax collection and payment ?

The tenants began pay rent on time, but then payments began coming in late, then half, then partial, then none.

Is it better to keep adding equity by doing work on the houses while I'm renting them then refinance to recover the initial down-payment to reinvest into another property or to pay down the heloc?

. - Inefficiency with payouts and administration will be compounded as the FAIR Plan has zero experience with a major pay out and lack infrastructure of assessors and technology to distribute the funds they don’t have.

I have done over 30k reservations and only had 1 instance of a guest causing above $10k in damage, so not sure how worth it is to pay for additional coverages. 

Quote from @Jaycee Greene: Assuming you pay asking price, I'd estimate the down payment for something like that using a hard money loan (HML) would be around 40% of the purchase price and your monthly payment would be $2,600 with an interest rate in the low 7% range (probably need a 700+ credit score to get that).

It may sound nice to pay a 6% management fee but the extra fees can add up to be more than the other company that charges 10% with no additional fees.