I have started the draft for my parents and there are lot of variables

. If I can get some help from the community here, I will be obliged!
1. Section 'Tell us more about what you'll do in Canada. Include dates.'
>> I am applying for a Visitor Visa to visit my son 'XX' and daughter in law 'XY', who are on a work permit in British Columbia. The purpose of my visit is to spend time with my family and celebrate the birth of my grandchild (expected date - 2026-07-10). I will stay for a month duration (2026-06-30 to 2026-07-30) and will return to India after my visit, as I have ongoing business, financial assets, and personal commitments that require my presence.
2. Section 'Names used in the past'
>> Unfortunately both mom and dad are using different combination of middle and last names across different docs like passport, banks, education, even their old marriage card. These docs would have middle name absent, other times only given name. All the docs except marriage card, have the same first name. I was thinking to simply add all of those combinations in the application section. Also, the applicant(s) name would be as mentioned in their resp passports.
3. Section 'Are you applying on behalf of someone else?'
>> Yes and then my details. Also, my details for 'who is inviting'
4. Section 'Finances' > How much money do you have for your stay in Canada? (In Canadian dollars - CAD)
>> This one is a little tricky. Would really help a definitive answer against my situation. Since the overall application is for a group of two - should this be filled with what each of them has in their bank? How much is a good amount? I don't want to be like yeah 'N' is a very good number but is probably very close to the total asset each show under their belt.
4.1 Finances > Is someone else giving you money for your stay in Canada?
>> I will be booking their tickets and they will be living with me and I will manage everything for them. My hiccup is if putting a 'yes' takes the application to a negative light for the parents? Should I provide my Canadian finances proof in any case?
4.2. Finances > Please provide details.
>> Need some help on this if answer to previous question is a yes.
5. Section 'Information about education, work and other activities'
>> My dad is a private businessman and description is 'Commission Agent - buys and sells goods, typically agricultural produce, in a local vegetable and fruit wholesale market'. Looking to confirm if below selection is alright?
Work or Activity = Sales and service occupations
Job title = Sales and account representatives
Company or employer = Self Employed
6 > Marriage Certificate
>> Yeah, I got to know my parents don't have a marriage certificate. It was not a norm back then. What are the alternatives?
Based on all above, what should be added/mentioned/omitted in the letter of invitation, funds proof + additional documents (Any additional documents or explanation that you think may assist the processing officer.). !!
So many questions but and I am avoiding AI on these topics. Thanks in advance