Welcome ((Arcira36)), Sorry for what brings you here.
Read the stickies above and other posts. The first thing you will learn is we are powerless over the Addict and the disease.
I would also recommend you and your parents attend some Nar-anon meetings. The A all have there own bottom to hit and only they know where that is. I want you to know that any monies spent on them (re: rent, groceries, etc...) only allows them to spend what ever else on the drugs. All you can offer is support, advice, and love. It affects the whole family.
I am sorry there are children involved, maybe someone can offer to take the kids in till they can get there lives back together, and seek help. [That would be better to do than your parents paying rent.]
Keep reading and posting. There will be others along soon with more advice and help.
Sending strength and prayers.
Your not alone....