Taking my Filly away from my Mare?

I have 3 horses; 1 year old Filly(flicka), 3 year old mare(Bella) and a 17 year old pony gelding(midnight) Btw Bella isn't Flicka's Dam. My grandpa, who owns horses but lives about 3 hours away asked me the other day if I wanted him to take Flicka down to his home. in a way i want to let him but i don't. see i can afford 3 horses and i have enough land and everything but it would be easier with only 2 on me, if you know what i mean. Im not worried about flicka because i know she will be taken good care of(he has 5 other horses, she can play with) but im worried about Bella. i really don't know how she would act. i have midnight, who couldn't get out and play and follower her around like flicka does. she gets enough exercise from me riding and lunging her but ive heard of horses getting depressed if you take there buddies away? anyway, do you think im just worry for nothing and i should let my grandpa take flicka or should i keep her? i think i answered everything but if you have any questions just ask. Thank You!