measure with multiple conditions

Your sample data doesn't match your description.  You say "Project B"  but you use project numbers.  Assume you meant "phase B" ?

How is the user selecting Phase B? 

You can easily create a modeling experience using "What If" parameters. What you cannot do is expect any persistence.  Meaning if you change the data for phase B of project 1 it will also change the date for phase B of project 2.  Power BI has no memory. There are ideas to that effect but there is no roadmap.