The answer to this has very little to do with victims’ advocacy. Instead, it has to do with political considerations that all advocacy groups must face. The answer must surely also depend on the nature of the compromises that are being suggested.
There is nothing special about victims’ advocacy groups when it comes to political calculations such as these. All groups have bills that they want passed, and many of these bills touch on issues that are vitally important to those groups. When compromise amendments are proposed to such bills, it can feel like an attack on the groups’ core values. At that point, groups have to decide whether the amendments make the bill so bad that they would prefer to have no bill at all.
If would say that a group should accept compromise on amendments if the resulting bill would still advance its interests. There is a saying that people should not allow the perfect to be the enemy of the good. In other words, people should not reject options that are merely good in futile pursuit of options that seem to be perfect. If victims’ groups reject all compromise amendments, they will be losing the good parts of their bills along with the bad. In a democracy, most policies come about as a result of compromise. Those who are unwilling to compromise will generally not get anything unless/until they can build an unassailable majority.
So, I would argue that these groups should accept compromise unless the compromises that are offered take away everything in the bill that is worthwhile.