Take a look this video about legato rolls from drum to drum and give it a try.
In this exercise above practice moving from drum to drum while rolling. You’ll have to switch your lead hand during the roll so that you can move to the next drum smoothly.
Practice playing a slow tempo with half notes and gradually increase your speed.
You will switch from right hand lead to left and lead when you move to the low drum and you will switch back to right hand lead when you move to the high drum.
Here is the same Legato drum roll exercise but for four drums
