Bootstrap Theme Update and Child Swatches On Update

Working on a potential Child Swatch for a cient based on the BS3 theme and wondered if an when the base theme gets updated I will have to go and update the files to re-point to the new swatch?
I doubt they would come back to me for those kinds of changes in the future so I need to know to document if required…
ie. // Register option for bootstrap themes
Adding my new swatch to the list…
Would it be better to push a complete new CHILD THEME in this case as described here…
https://pkp.gitbooks.io/pkp-theming-guide/en/theme-bootstrap3.html