Is that even legal? Most BMs would make you pry it out of their cold dead hand. 

DELETED<If your husband wants to hand over cash to SS...> 

Hmmm. So he wants to just shunt the cash to SS? And you have no say so?

Id be upset.

Are your and DH’s finances separated?  If they aren’t I would start working on getting that done.  This way if in fact SS17 does not end up paying his bills and DH continues to cover him it is coming straight out of his pocket and not your shared money.  It would appear your DH has done nothing too little to prepare SS17 for what reality is and paying bills, handing him an extra 700 on top of whatever DH continues to cover for him is not going to make SS17 suddenly realize how to budget and manage money.

It's not legal. It's a really bad mistake. It will backfire. I don't recommend. Support is court ordered to the parent and not the child. It is meant to go to the parent. Sometimes it helps with things like bills and mortgage. Which is why it needs to go to the parent. 

I don't personally think that giving a child support money is a great idea.  

As an alternative plan... Could he funnel the money away into an education savings plan for college /post secondary ... Add the funds there each month saving up. That's what I would do. 

If his son will still be living in your home.. then the CS is meant to defray and compensate your SO for his Ex'es portion of the cost of that support.

I don't have a problem, in theory with your husband using the money to pay for your SS's insurance and vehicle costs. .(assuming the kid has a reason like school or work to need to drive).

I think it's a mistake to hand over that full 700 though.. without stipulating.. oh.. and your "rent" is also 200/month.. and your car payment is 250 and your insurance is 100.. so you have "net  150 to spend on incidentals and fuel.

Sure.. helping his kid learn to handle money isn't a bad thing.. but just handing over the cash without monitoring and ensuring the money isn't used on useless crap is not going to teach the kid anything.

I would also factor into things how your finances are generally in the household. . can your SO pay for 2/3 of the costs of the home without needing this money?

That check is meant to pay SS18's living expenses. If he's living under your roof, some of those funds should go to pay for his room and board.

If DH is going to just hand him the check, then it's time for ADULT SS18 to pay his SHARE of the living expenses. I would tell your DH that you will be charging HIM room and board to pay for SS18's share and he can get those funds from SS18.

And if he disagrees and SS18 sits on his butt under your roof living off that money with no job and no college, they can both move out.

I missed how handing $700 a month teaches responsibility. If it takes care of his needs (insurance, car repairs, etc) and DH provides room and board, than everything SS earns goes for fun. At 21 he has a kid who has no idea of managing money.

Plus what are the odds that at 21 when child support ends is DH going to cut him off? My guess is no and DH'll continue to pay him out of his funds.

I doubt you can stop DH from this path. But, you can make it uncomfortable for him. Add up your house bills - mortgage, taxes, utilities, etc. Figure out the cost locally to rent a room and deduct it from that amount. The remainder you divide in two. SS pays the room cost. DH and you each pay the half amount. If SS does not pay, DH pays his share. If you don't have a joint house account to utilize for this, get one. 

Food is another issue. At a very minimum I would not buy anything special for SS. If he wants X for his snack, he needs to buy it himself. If DH does the food shopping, go over the bill and itemize any just for SS. DH either pays that himself or asks SS for it.

A much better plan, in my mind, is for DH to put some of that money aside. Either for some future schooling for SS or, if SS becomes responsible, toward a house down payment or wedding gift.

SS should pay rent and part of the grocery bill and utilities if DH gives him the child support money as it is suppose to help with living expenses. This is one of the dumbest ideas I have ever heard. If DH wants SS to have the money, he should put it away in a college fund.

If BM gets wind of this, could she take him to court to stop paying as he clearly does not need nor want it if he's giving it all to a kid who stays at home and has no bills? I'm pretty sure she'd love to not have to shell out 700 a month.

Giving his son this money would make a mockery of the whole CS system. If he wants his kid to learn about money, he should be helping him find a job. You learn a helluva lot faster when you earn it yourself. 

To make up the money the household looses.  And DS must start paying for things.  Room and board. Total cost of running your home divided by the number of rooms. Each room pays X amount each month.  FOOD  total food bill of household divided by 3 he pays 1.3 of food.  He pays his medical insurance, his dental bills and any  other thing he wants . Car,car insurance, cell phone 1/3. Ect, ect. Make a spreadsheet and list all money going out each month  and to who.   Internet. Cable tv. 

CS is paid by the NCP to the CP for the support of the kids.  It is not paid to the kids. 
 

Responsibility would be SS having a job to earn the money to pay his insurance.   A 17yo has no business getting  nearly $800/mo  in allowance.

That is a recipe for disaster.

Daddy is naive.

Well, as a legal adult he can pay 1/3 of the household bills. Hill to die on. If he's living with you- you only contribute 1/3 to the house. DH can do what he wants- but so can you.

The purpose of child SUPPORT is to assist the parent finacially who is SUPPORTING the child. The way the son learns financial responsibility is if he gets a job and budgets the money. Is he still living in your home? Eating your food? Taking showers? Using the internet? Is he still in school or going to college? If my mom handed me $700 a month at that age, I doubt I'd be saving it and balancing my check book. I don't know how well I could tolerate DH making up his mind and having the final decision about a situation he lies about in the first place. Don't forget that you can make final decisions too!