The answer requires an analysis of their Marital settlement Agreement and final judgment. It's hard to say from what you have said but barring access to the house until she starts paying would be one idea. Another is deducting the extra he has been paying from her share of the proceeds when the house is sold. Good luck.
Why not have them give them to you as a gift now? Then you can do whatever you want with them immediately. There are hundreds of web sites on gun safety. Surf the net and you will find plenty of information. Keeps guns clean is extremely important. Do not let them rust up or get dirty on the working parts or you are asking for big trouble.
If you have maintained a relationship with the child, but are being prevented visitation, you could petition the court for visitation rights. This special grandparent visitation statute applies to your situation.
(3) Special grandparent visitation provision. The court may grant reasonable visitation rights, with respect to a child, to a grandparent of the child if the child's parents have notice of the hearing and the court determines all of the following:
Your question lacks enough facts for a good answer. If someone owes you money, and gave you a promissory note, and failed to comply with the terms of the note, you need to make a demand to be paid. If you are not paid, then you could go to small claims court if the amount is less than $10,000. The Wisconsin Supreme Court web site has the forms and instructions you need to do a small claims action. If the amount is more than a few thousand dollars, you might want to hire an attorney.
You need to consult with a criminal defense attorney ASAP. There are plenty in Wausau. Try google and the yellow pages. If those don't work, call the Marathon County Bar Association and they may be able to point you to a few. This will cost you some money, but a conviction will cost you a lot more. Don't wait, get yourself an attorney now so he/she can advise you and deal with your situation.
In Wisconsin, any time an attorney believes the fees will be more than $1,000.00 the fee agreement with the client must be in writing. You can always make a complaint to the Office of Lawyer Regulation. I would consider that.