By stipulation only!
PAPIRAR:
Well, you could have dismissed without any adverse consequences against one or both of the defendants with a simple form, but only before the counterclaims were brought, which in effect turns the defendants into plaintiffs and you into the defendant for the purposes of the counterclaim.
Of course you can dismiss against the non-B.K. party if you wish, but that will not erase her counterclaim against you and that cause will proceed to trial, unless, the dismissal is mutual and done with stipulation. To do that, you and the non-B.K. party will have to get together and agree to extinguish your claims against one another and go your separate ways and it is of absolute importance that you both stipulate to the dismissal WITHOUT PREJUDICE. That simply means none of the parties can open litigation of the (same) causes of action at a later date (and while of course within the applicable statutes of limitation).
By the same token, you cannot file any notice with the civil court to dismiss the other defendant in order to remove her to the bankruptcy court as one has nothing do to with the other and you will basically have to go through the same motions with her as you will with the non-B.K. party, and here where things get a little confusing and tilt in her favor and you have to make sure she does not doubly benefit from the proceedings.
Because reaching of any type of accord with the B.K. party at this time is all but redundant; it will be of no benefit to you and of no consequences to her as your claim against her will almost certainly be discharged in the bankruptcy. You can certainly attend the meeting of the creditors and oppose her petition, but unless you show fraud, your claim against her will be discharged. That will leave her counterclaim against you in the civil lawsuit because whatever favorable judgment you attain will have already been rendered meaningless by the operation of the B.K. discharge.
In other words, she is quite smug and nonchalant at the moment and has no motivation to play ball, but you will have to give her a reason to sit up and pay attention.
If she does not prevail in the civil case, then so be it and that is the end of that, but, if she does prevail, it will probably be in the same amount and nature as your claim against her (or thereabouts) and you will have to make sure it is offset pro tanto. But for that to happen, you will have to still be alive and have standing in the civil suit, which you won't have if are discharged before the matter is decided.
So, the best move here would be for you to attend the meeting of the creditors and ask the trustee to withhold discharging against you as a separate civil action is pending the outcome of which will directly impact her petition and the creditors.
All this will of course be avoided if you can also get her to stipulate to a mutual dismissal with prejudice.
fredrikklaw