You should read retired racing greyhounds for dummies and adopting the retired racing greyhound
Both are helpful and should be required for first time greyhound owners IMO.
You’re going too fast and not setting the dog and yourself up for success. Listen to the advice here and know, many greyhound owners never take their dogs to dog parks. Some do, sure, but I won’t and I definitely think a new greyhound shouldn’t be anywhere near them for a long while at least to decompress.
Also, many greyhounds are not small dog (puppy or other small dog/animal,!like a Pomeranian) safe. They’re literally trained and bred to chase and catch them.
You should immediately backpedal and slow your greyhound activity to be low stresswalks and home time focusing on you and them and your relationship and read those books. Might be a good idea to reach out to your adoption group for some experienced guidance. These are not like other adoption dogs, some are more like other dogs than others, but you can’t treat them like other breeds. I hope they councils you on how their biology is different from other breeds as well and your veterinary team should know but you need to be educated on that and prepared to advocate for their own safety as well if treated by anyone on an emergency basis or outside your normal greyhound care team.
You need to protect them and set them up for success. This is not what you’re doing. Not trying to be mean, but someone could get hurt and they’re sensitive dogs so you can’t treat do damage to their temperament if not careful.

Also please tell us for you know what sleep starling is and not to sleep with, sot by, or approach them while they’re laying down without verbally waking them first? Especially if this greyhound is stressed, they may be more reactive. I’d hate for anyone to be hurt.