There are a couple of ways to accomplish your goal but I think that the easiest way is to create a custom design for these mixture components and then replace the runs in the resulting design with the combinations you already have. You can then augment this design with new runs that will complement the existing data.
JMP creates meta-data at the column and table level when you design an experiment and make a table for it. The other way is to enter the existing data and create the meta-data by hand. I have done this many times but it is tedious work so I suggest the first way.
I think it is a great idea to re-use existing data as long as it can be qualified for the new purpose. The existing data might be inadequate for fitting the desired model but augmenting will improve the data considerably.