Good question. I wouldn't be worried about litigation. Your (normal) worst case might be penalties from the OTA, a difficult ongoing relationship with their Market Manager and perhaps listing removals. All independents can find ways to reward their most loyal clientele, without market visibility. Happy to discuss this briefly over a call to share the tricks.

OTA is a sales channel, one of the many out there.
If you are trying to capture OTA's clients (individuals) and make them your own direct client try this
1- Signup clients to your hotels loyalty membership program and tell them that they will get additional benefits and discounted rates
2- Promote special rate in your website directly to your clients
3- Provide voucher, letter or etc... "upon your return you will get......"
4- Always direct your clients to your business directly..
Litigation?
Emails, website, social media, memberships etc.. is a way to promote your business, so basically you are promoting your business in many channels, if your contract ties you down sit down and review your contract with OTA before renewal.. Talk to them face to face and explain, much better solution,
Feel free to drop me an message if you need to explain more..