My corydoras will attach eggs to anything: Glass, leaves, filter intake, heater. The only places they don't seem to like laying eggs is on the driftwood or rocks. The really successful batch of eggs that made it to maturity were laid on a pennywort, and I just took that whole plant into a net and set it under the outflow of the filter in the fry tank. I ended up with 13 fry altogether that lived (3 died for mysterious reasons) and they're still thriving. Just put them back in the adult tank.
So you put the eggs under the filter outflow (how much flow is too much?) in a breeding net, let them grow in there for a couple of weeks and then re-introduce?