Tracking revisions in draft?

Hello! I need help.

I have an issue with revisions. Let me try to explain myself to the best of my abilities.

Let’s say I have user 1 and user 2.

User 1 creates a revision and submits it. However, it is not yet approved or published.
A few minutes later, User 2 creates a revisions and submits it as well. However, it is not yet approved or published.

This is an issue because when User 2 makes his revisions, I lose the revisions made by User 1 when I approve revisions made by User 2 and vice versa.

Here is a more concrete example.

Imagine you have a published post. Content is the following:
“Hi World!”.

Now User 1 goes to create a revision and submits:
“Hi World! How are you?”

When User 2 goes in a few minute later to create his revision he only sees:
“Hi World!”.

User 2 goes on to add his revision:
“Hi World! What’s up?”.

When I come to approve, I can either approve:
“Hi World! How are you?” or “Hi World! What’s up?”.

Would there any way for User 2 to see submitted revision and add their own revisions. And then as the person who have capabilities of approving, I would approve both if I wanted to and it could look something like this:
“Hi World! How are you? What’s up?”

I hope I was clear and I hope you can help!