DH thinks it is favouritism.
Dd1 is almost 9. Dd2 has only just turned 5. Dd1 is fairly well behaved and mature for her age. She sleeps, she listens, she understands no, she might sulk for a while but she is past throwing full on strops.
Dd2 does not sleep. Ever. Midnight is her typical bedtime. She'll still still be up and raring to go at 7am. On bad nights you can expect to be awake until 3am or beyond with her. She has no fear of anything and thinks nothing of running off somewhere and not telling anyone. She doesn't listen to anyone. If she is made to listen (one example would my mum telling her to move away from the edge of a cliff only to be told NO by dd2 and then physically attacked by her when she had to drag her away) Any attempt of discipline is met with violence or a tantrum lasting hours.
So AIBU to think that until she is older and calmer and has some regard for her own safety, then expecting relatives to care for her for a weekend is unreasonable?