You can pre-define the parameter names for a symbol from both 3D and Drawing (using the Grouping and Variable Text Parameterstab). However, the parameters are created only in the 3D symbol instances (Model-Based Definition; MBD) as you place symbol instance. The created parameters are visible in the Parameters dialog box, and these parameters are further used for downstream manufacturing and inspection procedures.

When you place a symbol instance in MBD, only the parameters that are derived from the symbol customization grouping and variable text (Symbol Customization dialog box) are created in the Parameters dialog box. When you update the symbol customization, relevant additional parameters are created for the symbol instance and the parameters that are not relevant get hidden from that symbol instance. For example, if you place a symbol instance and the parameters defined for that symbol instance are WELD_SIZE, PREP_DEPTH, and GROOVE_ANGLE.

From Symbol Customization, if you modify parameters for the symbol instance to add ROOT_OPEN and CONTOURand remove GROOVE_ANGLE, then the symbol instance is updated to include newly added parameters and the removed parameter will be hidden.

Similarly, you can also modify by selecting an entirely different parameter group, where common parameters are retained and parameters no longer relevant will be hidden.