Grandpa Henry (refuse to call him Henry, Sr. …LOL) wanted her to go after true love but Regina’s mother wasn’t a fan of that so she shrunk her husband to keep him quiet.
What if Cora shrunk Henry Sr. (I’ll continue calling him that ;p) as leverage (as Regina points out in Hat Trick) so that Regina marries King Leopold! Cora could’ve sent him somehow to Wonderland. Either through Jefferson or somehow else.