Help pls! Sponsor my parents. What to do with IMM0008DEP?

[pockymeimei]

Dear all,

I am a PR and trying to sponsor my parents.  My dad is the principal applicant. As for the form IMM0008DEP, should I fill out my mom's info there and then signed by my dad as the principal applicant? I am confused. The instruction guide and the document checklist say the IMM0008DEP should be signed by the principal applicant (my dad in my case) but the info filled out is all for my mom? Or I don't even need to fill out this form with my mom's info?

Thanks