Can a credit union holding a delinquent HELOC loan (2nd)sell the loan to a collector?

Can the house be taken into foreclosure by the collector? Adding charge off to the credit report, does that release the credit union from the deed of trust? Is not the homeowner to be notified if a transfer has occured? The house is upside down by the amount of the HELOC Loan. If a lien is placed on the property by the Heloc holder -vs-foreclosure action (2nd), will the 1st mortgage then be pushed to second lein holder position (current on 1st and into the 1st year of modified loan agreement)