My mother applied for both of them together as a group. However, we do have to fill the application forms forms for both of them individually and submit all documents for each application individually.
Also, the application form itself has the option of declaring if the finances of the trip is funded by the applicant themselves or if the money is being given to applicant by someone else. This is where we made an error in my brother's application by declaring that he is paying for his trip. The proof of funds document though stated that it's my mother who will pay for his trip, her bank account statements attached and a declaration from my mother as well.
We then submitted a webform highlighting the disconnect between what's mention on proof of funds doc and what's mentioned on the application form. Requested correction in application form to say my mother is funding my brother's trip and reattached the proof of funds document.
I understand that over 22years is considered independent and logically a stronger case would be if they fund their own trip. However, since IRCC themselves have given the option to declare that someone else is paying for the trip, I m just hoping that this route is not a red flag for them and it is acceptable provided the bank statements submitted have solid funds.
Also, the fact that we have submitted a webform to request corrections in application form does complicate the application to some degree from the officer's understanding point of view.
So now we have 2 things to pray about.