Mod for spawning a craft attached to a particular docking port

[cpttails]

Hello
This is my first post here  and I'm hoping I can get some kind help since Google has failed me.
years ago,  I remember a mod that featured a docking port that looks identical to the Jr. Docking port, but could be used to load a vessel that would spawn attached to it, basically allowing you to spawn a vessle attached to any craft built with one as a component. However, I have been unable to track it down as of late, and I would like such an ability for a sandbox save I'm running.
Does anyone know what happened to this mod, or know how to write a script to achieve the same end?

Thanks for your time.