Consolidate or to Not Consolidate your Projects

Today we had a meeting going over a few future projects and it was brought up we could integrate the new project into an existing project that had 80% the same functionality. However, there comes a lot more complication with this short of merge.

For example, what happens if two people are working in the same project on two different pieces. The first person is finished with their piece and checks it in happy as can be, while the second person finishes later and his change needs to go in ASAP, while the first person’s change can’t go in till the end of the month. Now what?

Now in a perfect world, one would state that the first person shouldn’t check in their code till it can go in, or person two would get the previous version of the first person’s code.

At work we decided to keep the projects separate and not consolidate them even though it would share 80% of the functionality for the UI. But in the end, it allows us to not step on each others toes.

So my question is, how do you handle this?