It's not going to hurt her brother, may make his hair thinner there but if it did hurt, he would let her know. I wouldn't advise squirting anymore though because when you squirt her while she's doing it, you'll hit him and he's not doing anything wrong. I would ignore it and when it starts to bother him, he'll let her know. Just make sure you get them spayed and neutered and keep up to date with a vaccine schedule.
Good Luck!
Disclaimer: The above is provided for informational purposes only. As I am not a veterinarian -- the above should not be considered, or relied upon as, veterinary medical advice. I strongly encourage you to consult your own personal Licensed Veterinarian regarding any serious animal medical matter as they will be able to see and exam your pet.
__________________
Let me know if you have any other questions
Good Luck &
Best Fishes
