Already have 3 prongs installed by electrician in my 3rd car garage right against the breaker inside the garage for tesla L2 charger. That’s where some family member has been charging Tesla for the past 2 years. I got VW ID.4 and thru my utility company I qualified for JuiceBox enel x charger but it has 4 prongs. So my question is it ok to get y splitter from 3 prongs to 4 prongs and attach Juice box. I may need additional extension cord because the cord is not long enough for JuiceBox.

What will be the best scenario in this case? or is it better to replace 3 prongs plug to 4 prongs and then get y splitter. Is it even safe using y splitter from 3 prongs to 4 prongs?