Do we have the rights legally to withhold the use from her since she is paying for the vehicle and we are only the co signers on the loan?

You all have the right to use the vehicle. You are all owners. You cannot restrict her use as she cannot restrict your use. Now if you have a contract, which you can claim you have an oral contract that says our co-signing was conditional on your not extending your use to anyone but one of us, well then you can enforce such a contract. And oral contracts are valid in Washington, if acted upon within one year of the making unless there has been some form or compliance with the contract that might extend the time limit to sue on the contract. You did not say how long this arrangement has been going forward.? If it is more than one year, the failure to commit the agreement to writing may have voided the terms. I doubt you can restrict her from using the vehicle.? But you can also take the vehicle to use it, particularly if she intended to allow someone else to use it not any of you.

What is there to straighten? The owner and the operator of vehicle are liable for its operation.

If the age of majority in your state is 18 yrs, then she can conduct her own affairs. If she is on your insurance policy, take her off. You do have exposure, since are co-owners.

Get your name OFF of the title. Your daughter is stupid. You are on the hook for this accident because you are on the title, and she did not, and will not listen to you. So, as an adult, you let her screw up her own life because of not listening. You have only that control. If it is truly her car, then she can do whatever she wants and all you can do is get out of harm's way.

All owners can use the car and allow others to use it. As an owner, your daughter probably can allow her boyfriend to use it. But, as an owner you could lock it up in a garage. You daughter would probably then stop making the payments, and you would be required to do so. You also have insurance issues, depending on who has the insurance in place. Also, if the boyfriend caused the accident, you or your insurance company could sue him for the damages. This is a difficult situation, and you may be required to use other leverage against your daughter (like taking away her phone or other things you are paying for) since technically as an owner she can dictate who uses the car as much as you can.