I don't have any particularly strong feelings either way on this proposal, so I raised it with the Law.SE mods to see what their perspective was - as to create a migration pathway between the two sites we'd need to get agreement from the Law community as well (see this answer on Meta.SE). Their current view is that they see more drawbacks than benefits to the proposal, and haven't seen enough examples to justify the creation of a custom pathway.
I can see their point somewhat, as in the last year there have been just four migrations to Law.SE, the most recent having been migrated over six months ago. That's not to say that the number of migrations might not increase if a custom pathway existed that didn't require moderator action to process, but it does give an idea of the scale of the current situation.
At the moment I'm afraid it doesn't look like this request has sufficient support to implement.