The forms you are asking for, 0008, 5406 and 5669 are all for PR application. So they are only for those who want to apply for PR. Based on your description your sister is not a dependant and can not be included in the "PR" application. And you're already PR/citizen. Only your mother is eligible as a spouse to PA, your father.
1. 0008 form: Do I need add my sister and myself?
No
2. 5406 form: Do I need add my sister and myself?
No. but you both appear in your parents' forms under "children"
3. 5669 form: Do I need add my sister?
No.
A little off the topic:
PGP is a two-stage process. Sponsor (and co-signer) apply for sponsor eligibility. Then parents apply for PR. There might be a slight overlap of the two during the process, but generally sponsor should get approved first. (Not talking about quebec applicants, that's a different process.) Nonetheless IRCC want to see all forms submitted at once, and this creates some confusion as who is the applicant? I almost never see IRCC refer to the sponsor as "applicant", even on 1344 the sponsor is still "sponsor" while parent is under "principle applicant". So when you see anywhere in the guide that the "applicant" need to sign or submit on behalf of dependent, it is 99% the parent(PA).