Was originally intended that the Anaconda (and presumably others) would be able to field a small ship. This was changed to SLFs because they didn't want to deal with nesting ships. In short, not happening unless for some reason they've changed their minds.
I'm well aware. I assume it's more of a code thing than a balance thing. There should be plenty of available workaround hacks. One example (this assumes loading time for the small ship was the issue):
The small ship doesn't need to stop existing anymore. Plop the player into the big ship, make the small ship noclip and invisible to everything and magically tether it to the big one so it doesn't need to unload from the game. Teleport it 10km away if needed, just to be safe. A moment before it becomes invisible, replace it with a placeholder texture that looks exactly like it, which would complete the docking animation.
Hmm if you land your small ship in a starport and bought / change into another ship, what happens to your mothership then?
What happens to your ship if you leave your ship on a planet's surface and walk into a friend's ship? I don't know. I assume it stays there until you pick it up. You could order it delivered to a station. Unless you left it in combat, in which case it plays out, normally simulated.
Also, same as with having cargo, you can't change to another ship until you resolve this. Otherwise, players would repeatedly change ships and leave a whole bunch of them loaded.
Edit: If you leave the system while it is in combat, it gets destroyed. If it was not in combat, it gets treated according to your status in the system. If you're an Ally, it just gets docked to the nearest station (even in another system). If you're neutral, the same happens, but you have to pay the transport fee to get access to it again. If you're hostile, you get a report that it was destroyed.
If another player is in it, nothing happens.
As has been said an idea abandoned/rejected before the game released.
What happens to the newbie friend and his small ship when the large one is destroyed?
Can you swap out of the large ship to something without this module while the small ship is on board?
What is the situation if one of you is wanted and the other is not?
If docked, the newbie friend and their ship both get destroyed, as expected. If not docked, they're on their own.
You can. The small ship gets docked and gets left in the station. Unless you have capped the number of docked ships, in which case you can't. Same with trying to unequip the module. To load the small ship in, equip it like you would an SRV.
In case of small ship being wanted, it doesn't show until you get scanned. Then it changes to both of you being wanted. The big ship gets accused of smuggling.
In case of big ship being wanted, the small ship remains clean until getting its own bounty.
Appart from other things already mentioned, you know same small ships are pretty big, right? If we just go by weight, that size 6 slot you want to use for this can't even hold enough cargo to cover the weight of my Eagle.
For simplicity sake, we can go with the base hull mass and allow Hauler, Sidewinder, Adder, Eagle, Imperial Courier, Imperial Eagle and Viper. Those are all under 64t (c6 cargo hold capacity). I don't know how the sizes compare, but any of those that can geometrically fit in the texture should be allowed to dock.
Let's say a Hauler fits (not sure that it does). You equip it with with B-rated modules, all engineered to be heavier, load it full of cargo and dock it. You're still allowed to do that because the game doesn't take it into account for this step. Just like how the game doesn't take into account module mass when calculating shield capacity.
Any cargo held in the small ship remains in the small ship, no cargo transfer happens. However, the total ship mass along with its cargo gets added to the big ship for the purposes of agility and jump range. You can transfer the cargo similar to how you would transfer stuff between your suit and your ship.
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Out of 6 replies this has gotten so far, 4 are skeptic of the suggestion, 2 are supportive and 0 just flat out don't want it. Looking promising so far.
By the way, if anyone thinks of any other issues the devs might have, please point them out and try to suggest a solution to other mentioned potential issues. Nothing I've said in this post or the OP has to be the way I said it.
Edit2: If and when they get around ship interiors and they aren't able to deal with docking physics, make the small ship finish docking using that forcefield or a tractor beam, whatever it is that catches SLFs. No physics needed, just an animation of the ship moving on a predetermined path.