If you are referring to transactions which are displayed in the GUI as Invalid Transactions with status rejected. they are in Imp_transactionimport table. There is no supported way of moving them elsewhere.
What you are supposed to do is either to fix the cause of each transaction and then see if it will processed further. If not you may need to to make a corrective transaction and then deleted one in error. Deleting the is the other option.
Posting to WIP will take the transactions further from this table. To prevent that you can put transactions on hold and then they willn't be processed.
That is to say Imp_transactionimport is the system provided place where those transactions are parked. I do not know how much overhead they will cause.
Why do you want to have them elsewhere. Are you planning to deal with them "at a later date"?
For the data flow see eg