A number of institutions are "herding people through" before the mid-2018 start of the federal government's redress scheme, church abuse victims' advocacy group Broken Rites spokesman Wayne Chamley says.
"Individual institutions are rushing to lock people in before national redress can occur," he told AAP.
Dr Chamley said institutions like the Salvation Army are renegotiating top-up payments of settlements at amounts below what would be provided under the national redress scheme and locking victims in with a deed of release, stopping them bringing a civil claim in court.
"They might have got a reasonable amount under a national redress scheme but because a lot of people don't see that it's going to happen, they're accepting a lower amount in a renegotiated or a topped-up settlement.
"We understand there's dozens of cases going through at the moment."
Lawyer Judy Courtin said many victims signed away all future legal rights for a $20,000 to $40,000 settlement through a church redress scheme, when some may have been entitled to more than $1 million - including for economic loss - through the courts.
Dr Courtin said religious orders such as the Christian Brothers and Marist Brothers are revisiting old settlements and paying additional compensation.
"But are they paying what the claim is worth? Of course not. It's a top-up," she said.
"There are matters going through the courts now that are worth $1 million-plus, especially if people have never been able to work."
Victims' advocate Helen Last said many victims received very low compensation in past settlements, from the $20,000s up to the $50,000s for horrific abuse.
Ms Last said a number of victims had sought additional compensation after the Catholic Church's Melbourne archdiocese doubled its cap on redress payments to $150,000, in line with the Commonwealth scheme.
"But again the victims are coming to us in droves complaining about that process, saying the original amount of money they got from that archdiocese was so little, like $27,000 for years of assaults, and now even with application to the top-up system they're still only getting around $70,000."
The In Good Faith Foundation chief executive said some survivors are sitting on top-up offers from the church's Melbourne Response while they wait for it to become clear if states and institutions will join the Commonwealth redress scheme.
"Some are receiving offers that way and then sitting on them, not taking the deed of release and not settling them."