In this scenario (for the survey URL), https://companyname.questionpro.com would be the base URL, which cannot be changed for every client. (If a small correction is required in the base URL, we"ll do that for you).
The only way to differentiate between clients while using the live survey URL will be to use it in the latter section of the URL. For example: https://companyname.questionpro.com/XYZZ where the ""XYZZ"" part can be the client"s name, their company, etc.