You can amend your petition to exempt additional property as long as exemptions are available under state law. The Trustee will have up to 30 days from the conclusion of the 341 meeting to object to your exemptions.
Representing yourself in a Chapter 7 isn't as easy as you thought it would be, is it!
Once you file a Chapter 7, you can't just change your mind and dismiss it. You must have court permission to dismiss, and that can be problematic.
Hope this perspective helps.
You need to seek the advice of an attorney who practices bankruptcy law, because, you do not have an unlimited right to dismiss your case. However, you do have a limited right to dismiss, but that may come with bars to refiling. If you believe protecting the asset is worth a six month bar [used only for the purpose of illustration] to refiling, let the lawyer know.
Each Bankruptcy Case is very fact specific and not something you should attempt without legal advice from an attorney who has reviewed your entire case. Correctly completing the petition and schedules is difficult even for attorneys, it is not something that you should, "give a try to see what happens." I believe you will be very unhappy if you approach the matter in that manner.
If you have room to exempt the property you should get that done immediately, and you may need to have acceptable cause regarding why these assets were not exempted initially. If you are entitled the court will allow the amendment, unless the trustee can show you were trying to hide the assets.
Also do not try anything along the lines of repaying old debts to family or friends, or just spending the assets, thereby making them unavailable. Actions of that type will have terrible negative consequences.
Hopefully counsel, will evaluate your case and find nothing that an amendment can't fix, but get help. This is a "federal case."
The problem you have is that established case law makes it clear that outstanding (uncleared) checks are property of the estate, as are unreceived tax refunds. Whoever filed your case did not have an understanding of the law, and failed to exempt those funds. Now the Trustee has determined that those funds are rightfully available to your creditors, and is doing his duty to recover them for that purpose. You chose to leave those funds exposed to the Trustee, and he opted to accept them for the benefit of your creditors.
You always have a right to amend your schedules, but if the Trustee has expended time and effort toward the recovery of the funds, you may get some resistance from the court. The argument against you being that you purposely failed to disclose assets that were clearly property of the estate and now only after you have been caught are you trying to protect it.
And as pointed out by other counsel, dismissal is only with permission of the court. You have no right to voluntarily dismiss.