Generally speaking, any fillers or thickening agents designed for epoxy as an adhesive will be compatible with just about any epoxy adhesive. This can include additives from different epoxy brands, or different thickener brands. You can always check with the epoxy manufacturer to verify product compatibility or to determine if there might be potential issues. It is also recommended to try unfamiliar fillers in the epoxy first to make sure they achieve the desired results.
Colorants or dyes should always be checked to make sure they are designed for use with epoxies, because not all colorants are compatible with different resin types. We recommend that you always try a small sample prior to attempting a larger project.