Hello Rupa. If your sister is not interested in engineering then she can opt for many other options. Some of these are:

• AIME Certification Course- It is a course for professional certification and it is equivalent to the B.E degree. The course duration is of 3 years for diploma candidates. After the completion of the course she will be getting an AIME certificate from the Institute of Engineering.
•  If she is not interested in either of the two- B.Tech or B.E., then she can pursue graduation degree in her field. Degrees like BSc., BCom, B.A, etc can be pursued. It will be a normal 3 years duration undergraduate course. But the only condition is that she will need to pass 10+2 and have its certification.
• Since diploma students are trained for the practical field she can also opt for jobs. Many companies, both private and govt. sectors, hire diploma students. She can also try to explore self-employment opportunities.

I would recommend that you sit down and ask your sister to jot down what she likes to study, her interests, etc. and accordingly you can suggest her a stream as per her interests.

Hope this helps. For more queries please feel free to comment down below.

Good luck!