2 ways to skin a cat I guess.
I’m assuming the weighting of your clothes are done in your 3D program. Please re-read my post it will help you, specifically this part…
Our steps were (ill use your uniform as an example). Rig the Uniform to certain bones of the character and weight them so they deform like the character itself. Export just the Uniform with the bones etc…
Then when you import them into UE4. Import them as Skeletal mesh but instead of letting it create the skeleton select your Characters skeleton. This will work because the bone names etc… are the same.