About Drum's scere

Hello.

Now I wanna make a drum's score and place two different sounds such as Snare & Bass Drum at the same place. However as far as I look, some kind of sounds are categorized and I can't put another sounds in the group.

For example, when I put a sound of cymbals I can't put a sound of snare above or under it.
How can I manage it?

I'm sorry my English is poor because I am a Japanese student.