When creating a multi-response/dichotomous the 'base' variables are all kept in the file. So no variables are lost.
There is something to make clear:
+ in Editor Mode, variables will appear in 'grey' color which also visually helps to identify them as variable used to create a new multi-resp variable.It is possible to transform that 'grey' variables into 'black' ones which in Designer Mode will translate from invisible to visible.
+ in Designer Mode, all the variables that are 'grey' in Editor Mode are simply not displayed, default settings of Datadynamic since Designer Mode is conceived as an instrument to Design Tables.