How to work with clients who only have site plans?

Hi everyone,

Say a client has a functioning website hosted on their site plan (and they only have a site plan).

I on the other hand have an account plan (Lite or Pro). If the client needs me to perform a one-time modification to their website, what would be the best approach?

Do they need to purchase an account plan speicifically for this one-time modification, or is there some way to tie my account plan to their website to perform edits and modifications?