Asking for BP landlord wisdom on handling a tenant argument regarding additional fee/security deposit for a puppy. I’m in GA.

I just approved a puppy at one of my rentals. This is not typical, but there was a reason for this. Tenants agreed to pay a higher non-refundable fee of $450, plus extra $450 for security deposit –to reflect additional risk associated with a puppy (also not fixed until 6 months). They also pay animal rent.

At another property, a 10-yr old German Shepherd just died yesterday. She was one of the three animals approved at this rental (another dog and a cat) less than a year ago. At move-in, tenants paid $250 non-refundable fee, plus $25 monthly rent for this dog. Today these tenants tell me they want to bring a German Shepherd puppy to “fill the void”. I’m fine with another German Shepherd, and my insurance is ok with it. Puppy is a different story. However, given puppy approval at the other rental, I felt obligated to be consistent and said I’ll ok the puppy as long as they pay additional $200 in non-refundable fees ($450 as charged at another property, minus $250 they already paid for the adult German Shepherd), plus additional $200 for Security Deposit (really should be $450, I miscalculated). These extra charges are meant to reflect the risks specifically associated with a puppy.

The tenants got very upset when they heard about the extra costs. They bombarded me with arguments that they already paid the fee ($250 for adult dog), and that the lease already makes them financially liable for any damages, and that they didn’t want their dog to die and it’s unfair to charge them extra, and that they trained puppies before and know how to raise them without damage to property, etc, etc. I explained that puppies naturally tend to cause more damage and we need to reflect that in extra fees/deposit, and that it could be unfair/discriminatory to the other tenants if we don’t charge them extra for the puppy. I also suggested to get on older dog (1+ yr) instead of a puppy and avoid any extra costs at all – but they objected to that as well. We ended the call with no resolution. 

Now I am looking for advice on this situation. Should I not charge them the extra fees/deposit for the puppy? In addition to my concerns about property damage and possible accusations of preferential treatment, I feel giving in would motivate these tenants to demand more concessions down the road. They are fairly good tenants, pay on time, property is fine, but are far from the best tenants I had due to their growing attitude. 

Thank you in advance for your input!