The birthday party is not enough reason.
1. Submit a Joint account statement for Husband/Wife.
2. Past 3 years' Child/Children's School Tuition Fees and other class fees and Current years Fee paid slip as well.
3. Housing Loan document if it is available.
4. If it is own property, show the Deed documents or Bond documents with the name on them.
5. Show Travel history document only if traveled to U.K, U.S.A, Australia, New Zealand, or European countries. ( You still have to mention your other travel in the Travel History form.)
6. Letter from Employer
7. Leave approval letter from Employer.
8. Other investment details in India, local investment matters. LIC funds, or any other funds.
9. Car EMI or Vehicle purchase EMI.
10. Ties to family members - With pictures - Seriously write an essay-type explanation about your tons and tons of family members.
11. IMPOSSIBLE - If at all possible - Get a return ticket for her and attach it with your application.
12. On top of all this, she needs to have $4000 CAD equivalent amount in her Indian Bank account for the past 6 months.
For everything, write an individual explanation letter - I mean for every document that you submit. Explain clearly what that document is. Highlight your responsibility.
You in Canada -
Write a sponsorship letter - Get it notarized for 40$
Get your MP to write a recommendation letter. ( Usually, they will directly write a letter to IRCC as well.)
Submit your T4, Employment letter, and Income statement.