Unfortunately, a mathematical relationship between dilution (change in volume) vs change in density is not determined, and no guidance on diluting the product to yield a given density can be offered.
A similar product, product 71913 Sodium polytungstate, contains literature in the Description section in the 'DESCRIPTION' under 'Other Notes' regarding density adjustment:
M.R. Gregory, K.A Johnston N.Z. J. Geol. Geophys. (1987)
B.Plewinsky, R. Kamps Makromol. Chem. (1984)