i have four plots next to echother that i wana combined to make a huge city

We no longer offer conjoined plots, sadly.

why not?

First off, it would mean a lot of work for members of staff to combine all these plots. It would also cripple the plot expiration system; when a plot has expired and gets reset, the road around it would not be reset back to normal. All in all, it would ruin the terrain and in the end result in a lot of excessive work for staff members. Thank you for understanding.