favorite children

Jasie
My husband is not my parent-in-law's favorite child. And this could have been allright if not they made such a difference between him and his brother. You know, my husband was never in doubt about this subject. 
My BIL always recieve money for cigarettes, travels, clothes etc. He lives for free (at my parents-in-law) and my FIL even cleans his room and change bedsheets and wash his clothes. He is 25. They pay and make his food and when my husband once asked why they never gave him any money, they said that my husband earned enough. The brothers had the same pay at the time btw.
When my husband lived home, he cleaned his parents part of the house, he made the garden (and he still go over to help out, even just to cut the grass). He was to pay rent and of course paid for his own clothes, furniture etc. 
When the brothers each got their savings (we have a tradition of making a saving for our kids that they recieve either on their 18 or 21 birthday in DK) my husband bought a new computer and saved the rest. My BIL used it all on alcohol. My parents in law found out and just gave him some more money.
When they were kids it was the same. My husband was bullied and his parents didn't care. They didn't care. 
But this could have been somewhat fine but when my husband haven't worked on their garden for a while and he suggest to come over, they are like 'yeah you should, it's time' no thank you or that would be nice. When my husband borrowed the car and got a parking-bill my FIL got really angry and threatened that we could not use the car again. My BIL damaged their old car (that's why they got a new....) and they were like whatever-shit-happens-son. He even damaged the new one but it still works. And that how it is with everything; my husband does something and hell is here on earth, my BIL does the same or worse and noone bats an eye.
We have tried to invite them over for dinner  to have some quality-time without my BIL and his awfull girlfriend (she moved in with him and pay nothing as well, but don't get me started on that one) But they can't make a date with us, and distance is not the problem since we live 5 min apart walking distance. 
We are not in doubt about my husband not being the favorite child. And we know that parents always have favorite children, but this is just awfull. He has been treated so differently from his brother. But what can we do? 
I want to go over and yell at them all. Ask why they act like that towards my husband. Do you wise women have any advice?