addPickupAndDelivery group-linking constraint causes all multi-part ride requests to be dropped

[criptocoko]

Description:

I’m attempting to enforce an “all-or-nothing” behavior for multi-part ride requests in the Vehicle Routing Problem: if any pickup in a ride group is dropped, all pickups in that group should be dropped (and similarly served together).
I added a custom constraint to link the first pickup’s active variable to each subsequent pickup’s active variable, but instead the solver ends up dropping every multi-part request.
Example: user_1 goes from house->hospital and later from hospital->house. I need the solver
to realize if it can't serve the hospital->house part then it shouldn't serve the house->hospital part.

Code Snippet:

DROP_PENALTY = 1000000000;
// 1. LINK FATES: Enforce that all pickups in the group are served or dropped together.
// The addPickupAndDelivery constraint already links each pickup to its delivery.
// We only need to link the first pickup to all subsequent pickups.
if (rideGroup.size() > 1) {
    long firstPickupIndex = manager.nodeToIndex(
        rideGroup.get(0).getPickup().getIndex()
    );
    for (int i = 1; i < rideGroup.size(); i++) {
        long subsequentPickupIndex = manager.nodeToIndex(
            rideGroup.get(i).getPickup().getIndex()
        );
        solver.addConstraint(solver.makeEquality(
            routing.activeVar(firstPickupIndex),
            routing.activeVar(subsequentPickupIndex)
        ));
    }
}

for (int i = 0; i < allGroupSolverIndices.length; i++) {
    routing.addDisjunction(new long[]{allGroupSolverIndices[i]}, DROP_PENALTY);
}

Expected Behavior:

• If the solver chooses to drop the pickup (and delivery) for any part of a multi-part ride request, all pickups in that same ride group should be dropped.

• If the solver serves one part, it should serve all parts.

Actual Behavior:

Adding the above equality constraints leads the solver to drop every ride group that has more than one part—even when vehicles and time windows are available. Single-part rides behave correctly.

[criptocoko]

I couldn't find a clean way to enforce the "all-or-nothing" constraint during solving, so as a workaround I'm now trying to post-process the solution: after the solver finishes, I go through the solution and check for partially served ride groups. If I find one, I remove the entire group from the solution. How can I do this and keep the route 'optimized', I don't want to leave a space where the ride does nothing because i removed a visit from it

Is this a reasonable approach?
Or would it be more advisable to re-run the solver with those groups removed from the input entirely?
Is there a clean or recommended way to "edit" the solution after solving, or should this always be done via the model before solving?

Any suggestions or best practices would be appreciated.