I have it worked. Simple attach. In my case I use fps template, but with third person this is same.
here is before:
https://i.imgur.com/9ZqGP8S.png
here is result:
https://i.imgur.com/EbqIX7a.png
I can walk with this character attached where I want. It need more code, but attaching work as expected.
Here is attached to component weapon on muzzle:
https://i.imgur.com/TVpXPEc.png
Here code:
https://i.imgur.com/F1okBuE.png
Code is in Player blueprint. On screen when player is overlap by this character UE4ASP…, character is attached to weapon in socked muzzle.
This works also with attach to actor, but I think to component is better. Anyway, it need still a lot of code, but this character is attached and player can walk everywhere.
You can add code to start it with button or whatever you want.
You have to change character collision on hostage - it should overlap not block to check player is overlap.