Never use animations via skeletal mesh for anything that isn’t soft body in nature.
They should like brand that with hot irons on top of the FBX import or something 
The timeline suggestion above is likely the best way to go about it things.
Also applicable to doors, windows, etc.
Now Curtains are technically soft bodies, so you would use an SKM and cloth definitions on those, then combine it with a timeline to open/close them - still wouldnt bother animating the open/close animation personally, but you can and it wouldnt be against best practice, like in the case of a drawer…