Hi Jackie:
There is a low cost way to prevent feedback. Simply use a pitch shifting block to slighly modify the signal. SigmaStudio has a built in frequency shifter block. If you need a higher quality one, Base10Labs has a more mips intensive but better sounding Pitch Shifter. A trial for the Advance Pitch Shifter from Base10Labs will be included in the next SigmaStudio Beta.
Other more complicated ways of removing feedback can be done but nothing that is readily available on SigmaStudio. For this, perhaps you want to contact a 3rd party.
Regards
Miguel