Rename one of the metas vehiclelayouts_nameofcar, example vehiclelayouts_rx7.meta or vehiclelayouts_RHD.meta.
Then add the newly named meta to your content.xml like you would with a car mod, Example:

<Item>
<filename>dlc_MODDING:/data/ai/vehiclelayouts_rx7.meta</filename>
<fileType>VEHICLE_LAYOUTS_FILE</fileType>
<locked value="true"/>
<disabled value="true"/>
<persistent value="true"/>
<overlay value="true"/>
</Item>

AND

<Item>dlc_MODDING:/data/ai/vehiclelayouts_rx7.meta</Item>

So basically instead of merging them, you can just have multiple metas

You lot need to learn how to combine dlc's.
Instead of having 23 addons, have one addon with 23 cars.
There's tutorials and mods to help you learn, all you gotta do is search and look.

Im now getting the exact same problem, my game was working fine yesterday but today when i spawn one of my addons i fall through the map and gives me the number 4 error code

Ive already got that config and i tried the heap adjuster and no change

@cyber5042 Firstly, you dont need to touch titleupdate, only put the lines you need into the dlclist.

Secondly, are you using any scripts that use online maps? (Open All Interiors, SPA) because using online maps limits the amount of dlcs you can add. If you are, remove scripts that do use online maps and test.

The thing i always do is test each mod/script one by one to find what it is causing the crash, start with your dlc's, add one at a time, then the mods you use, then scripts.

I've been downgraded to smugglers run for ages now but since i downgraded I've been unable to make a new mods folder, I have to use the mods folder i created before i downgraded otherwise my game crashes loading into single player.

Does anyone know if there is a fix for this?
Only thing i can think of is i have all the latest files in my update.rpf which causes the downgraded game to crash?

Please try using the search function first, there's probably hundreds of posts with exactly the same question/topic.
I answered one only two weeks ago.. https://forums.gta5-mods.com/topic/16853/how-do-add-ons

https://www.gta5-mods.com/tools/add-on-replace-base-folder use this, its how i learned to combine add-ons. Read his tutorial a couple of times first to try and understand before attempting

You're better off using the one by Reyser, you can use it for more than just cars, plus the tutorial he's made is pretty in depth, I used his tutorial to learn how to do it all myself
Here's the link https://www.gta5-mods.com/tools/add-on-replace-base-folder

Would also be nice to have some form of the CEO/Biker business/Import-Export for single player too

I was going to request the same thing, it would be great if someone could make this happen!