Do you have close friends you can talk to?
I finally said a close family member had a drink problem and 3 close friends then told me their parent(s) had problems and all sorts of stuff which really helped. I never knew my best mate from school's mum was an alcoholic! We talked for a long time and it really helped both of us.
I have 2 BIL who have completely cleaned up and you can't do it unless you want to. You cannot beg/force/blackmail someone into seeking help, it does not work.
They have to want to do it for themselves, not their kids or partner or anything else. Otherwise they slowly go back to their old ways.
Addicts are very selfish and very manipulative and will do anything to service their habit so I would say:
Don't believe anything they say without trying to get another version or treating claims of what they have done with a pinch of salt
They really think it is not their fault, they have no problem, so tyou cannot have a rational conversation with them unless they admit they have a problem
Don't lend money, don't start agreeing to do things for them...they will use the time to get drunk
Find a support group, someone will always be able to top your story such as "8 months pregnant have to rush 400 miles to rescue mother after police say she has been wandering round town in the middle of the night in a disorientated condition" to find mother has discharged herself from hospital and has robbed an off licence
If you have a partner get them to remind you not to falter. I sometimes feel sorry for a family member and my DH only has to say "it wasn't 5 star ENOUGH!" to stop me feeling sorry for them! (this refenrecnes my drunk in-law abusing room service in the Marriot 5 star hotel as she thought they were too late coming with her meal).
Don't take their crapness to heart. They are throwing the drink down their throats, not you.
Don't clear up their crap, it's their mess not yours
Support them if they decide to clean up
Get on with your own life, don't make your kids suffer because they have decided to piss their life against a wall
Remind your self that it is their choice and they should take the consequences
..and it is hard...