If you are not comfortable scripting, you could potentially use a Virtual Join between the 2 tables to access data from "Data" into "Newdata". Here's a link to a brief JMP video on the topic: Virtual Joins - JMP User Community
If you are using the Formula Editor in "Newdata" for calculations, you could reference data from the "Data" table by using a column reference such as:
as column (data table("Data"), "my_column_data")
where "my_column_data" is the name of the column in "Data" table which contains the data you want to use in "Newdata".
I agree with Ian and Dan that scripting is the most flexible and powerful way to go. I myself prefer scripting but fortunately there are often several ways to get the job done in JMP even if you're not a scripter.