Stuck outside coal car. Can't open door?

[Peach Jelly]

Help!
On the triple-decker train level, I've finished gathering all my family members and went through the little cut scene. Now we're all standing outside the coal car, and I have no idea how to get the door open. I'm unable to stack with any of the family members. When I click the action button, the mother says "No time for that now! I must open that door!" And I can't leave the area because the baron's guards closed a gate leading back to the previous area. What am I supposed to do?

https://steamcommunity.com/sharedfiles/filedetails/?id=2298516066

https://steamcommunity.com/sharedfiles/filedetails/?id=2298516541

[Peach Jelly]

Solved: For anyone else that may been experiencing this issue, it was a bug. I had to exit to the main menu and reload the save. Now I can stack like we're supposed to be able to.