I tried to answer this in the question you asked it in. https://support.mozilla.org/en-US/questions/1446861#answer-1652297 I do not recall charter ever supporting carddav for contacts, so I assume you have contacts in Thunderbird only. If that is the case then they will stay in Thunderbird. If they are on the charter mail server then you will need to export them from there and import them to thunderbird or gmail.