There's need to improve it. As it's a story of society they can change, add, remove as many characters as they want. In all societies owner Can sale his flat or if is not staying he will give his flat on rent.. That way new character will come in and old will go at least
for some period of time. They can also bring /Show Daya bhabhi's Mother, (like Daxa chachi) Popatlals wife, some Muslim family,... And so on
Unfortunately they don't want to go beyond thinking.. There was lot of variations in the real stories of Tarak mehta