Car extra and suspension issue

[Algonquin_Hood]

Hello, I have the following issue:
Extra parts detach parts they are not supposed to detach.
https://gyazo.com/885266944437b441aa3ccdeb81f22f77
For example, if I take extra_3 off ingame, it will make the front bumper disappear.
Removing extra_2 will make extra_1 disappear
I tried moving it upwards and downwards in the hierarchy, moving the Children around but that didn't help.
https://gyazo.com/e6e1167884b455115db88042729be9ee

Second issue is the suspension. I moved the dummy to every plausible position, but it always moves like this under compression:
https://gyazo.com/42dafbbf92a29eaa459b906e13c3cb78
Obviously it's supposed to compress, instead of going sideways.

Thanks in advance

[Oleg]

add collision to extra object.

[Algonquin_Hood]

add collision to extra object.

Thanks for your response.
I added collision to all respective extra parts, no improvement whatsoever (collision works ingame). Just out of curiosity I moved all extras from the bottom of the hierarchy to the very top. Extra 1 works completly fine, Extra 2 and Extra 3 make anything below them in the hierarchy disappear.
Also, here's a better view of the suspension situation:
https://gyazo.com/f095b92e8fae097d41dc0e9d7707cd61

[Oleg]

import model back and ensure hierarchy is 100% retained (matches the one on export), including location of COL objects in hierarchy. Also, try a "gta_parts.xml" fix, it might be related to the issue too. the file is attached to a sticky guide thread on top and should be placed into "Install" folder.

[Algonquin_Hood]

I controlled the hierarchy and everything is the same. I also exported with gta_parts.xml but nothing changed. I worked my way around by removing one of the faulty extras completly, so I'm only left with one faulty extra now. Placing that on the very bottom of the hierarchy fixed the issue. As for suspension, dummy is on the same position on the suspension mesh as it was on the car I took the original suspension dummy and mesh from. Reseting axis to parent didn't help, so I went all lazy and attached suspension mesh to my transmission_f and transmission_r mesh lol

EDIT: I also found the dials to be missing. I remember fixing this on one car by just grabbing dials and their material from original Rockstar model and merging, but it doesn't seem to work on this project.

[tall70]

Then try some different experiments, if you have more than one extra like 3 or 4, remove one temporarily see if it's gonna suddenly work, maybe it's gonna isolate some accident mistake. I had extras functions completely messed up, then I removed extra 12 coffee cup and Bam all extras worked as intended and set up in hiearchy