As per answers to this question What can break a Vampire’s Charm besides Greater Restoration? - a vampire's charm can be challenging to break (i.e. Dispel Magic doesn't work) but the charm can potentially be broken by separating the victim and the vampire onto different planes.
Separating a charmed PC onto a different plane might be accomplished by having that PC step into a Bag of Holding or climbing a Rope Trick into an extra-dimensional space. Getting a charmed PC to do this could be challenging. A Bag of Holding is a small space for a humanoid.
Additionally complicating just asking the PC to enter the extra-dimensional space is:
The Charmed target regards the vampire as a trusted friend to be heeded and protected. Although the target isn't under the vampire's control, it takes the vampire's requests or actions in the most favorable way it can
The vampire could conflict the PC by requesting they do not enter either space.
How would we and what are the guidelines around forcing such a charmed (i.e. potentially unwilling) party member into a Bag of Holding or into the extra-dimensional space created by Rope Trick?