When they exaggerate stuff between couples or husband-wife relationship in these tv shows, then it's obvious that it would happen in other relationships such as sisters' as well. So far they have done a decent job in this department.
I also agree with Anu on Manvi bit. The actress is doing quite a good job in her portrayal of the character of the younger sister. She stands out in almost all scenes and with any character. She seems to balance humor and emotional bits quite well.