she clearly understands the entry requirements, she is asking about something which is a grey area (some people have successfully converted STVs to other visas despite it not meant to be allowed) but you only answered her question with useless unfounded speculation which is off topic
Can you extend it? I'm not sure of other options except for volunteer visa and covid extension you can get easily but might not be around until April, of you can keep the education visa until then that's probably the easiest way