substituting a snare drum sample for the original

I’m recording a drum track with the electronic drumset “Roland TD-4KP” V-drums portable set, and I’ve created a snare drum sound/sample (not on the drum kit but on a cubase) that I want to substitute into the track instead of keeping the electronic drum set snare. Problem is, I don’t know how to put this sample in, in order to replace the snare sound on my electric kit in the track.
Things I’m unsure of:
1.) When I try and put the snare drum sample into the track that I have recorded with my electric drum kit, it automatically goes to the start of the bar which is not what I want, when I want on beat 2 or 4 for instance.
2.) I need to keep the hi-hat in the track as well, and it looks like it won’t stay if I insert the snare drum
3.) I don’t want this sound only on the backbeats either, I want it to be a constant feature of the track.
4.) The process to do this.
So is there anyway I could:
1.) Substitute the sample into the track to replace the snare drum sound on the electronic drumset used to record the track?
i.) (Not only for backbeats)
2.) Download the sound onto the electronic drumset itself?
(Using cubase AI7 by the way)