Cargo Bay - It should work .. but why cant I get it to work

[Bestia]

O.k .... I am still new at modding ....

So I have ... Borrowed the 1.25m fairing from Nova Punch

And made them into Cargo bay walls

But I have two issues

1) How do I make the sides join up .. because currently they only connect end to end?

2) The "Door" (in the example ship the bottom quarter) will not connect to the door hinge from the Damned Robotics

I have included all the "Cargo Bay" parts including Damned Robotics V1.2 and the Cargo POC that I am using to test with - You can get them here

Why do I want to make this, - Well to start with my next step is going to be create a beacon that can be dropped from a plane/orbiting craft that will make places of interest easy to find. It will also make driving easier, because you fly your cart where you want to go .. land .. unload ... drive around and then pick it back up again ....and cause as far as I can see no one has attempted it this way before

Any help would be great

Now when I say borrowed ... They are my template ... Something that is working, that I will slowly recreate, using them as guides, so I know how I want it to end up, but learning the skills to get it there ....

Thanks