Setting up interdependent worksheets

In spreadsheet 1, I have a unique list of text items (Column a). This
spreadsheet is added to, resorted, and updated continously.The data is
arranged in rows and has a variety of formulas. One formula is a reference to
a value on spreadsheet 2.
On spreadsheet 2, I need to use the resorted, updated list on Spreadsheet 1.
This list would be copied/matched/indexed? My confusion is because
Spreadsheet 2 is also constantly changing so a simple cell reference will not
work.

If the data was fixed in either sheet, I could work it. But don't know how
to keep the rows in each sheet, and allow for filtering sorting etc in either
sheet.

Spreadsheet 1
Project,Value from spreadsheet 2, other data columns specific to each
Project row
Spreadsheet 2
Project from spreadsheet 1 in rows, Value, data and formulas needed to
determine Value column. Value specific to each project.