EU Family permit for Parent refused

Hello guys, I applied for my mum Eu/EEa euss family permit. 4/5 months got decision this week and REFUSED
the reason is
You have stated that the family relationship of the EEA citizen sponsor to yourself is dependant parent in law. As evidence of this relationship, you have provided a birth certificate for your son issued 16 November 2016. However, this certificate is not a format that is accepted by this office and contain discrepancies that lead this office to doubt their authenticity. As a result, it cannot be accepted as reliable evidence of your relationship to your sponsor. Without further historical documentary evidence or other credible documentation evidencing their parentage, I am not satisfied that you have provided sufficient evidence that your relationship with your sponsor is as stated.
Next Steps
If you have further evidence you want us to consider, you can make another application under the EUSS Family Permit at no cost:
You can also appeal this decision to the First Tier Tribunal under the Immigration Citizens’ Rights Appeals (EU Exit) Regulations 2020. You have 28 days from the date since you received this decision to appeal.
You can appeal on the basis that the decision is not in accordance with the EUSS Family Permit Rules, or that it breaches any rights you have under the Withdrawal Agreement, the EEA EFTA Separation Agreement, or the Swiss Citizens’ Rights Agreement. You may bring or continue an appeal from inside or outside the UK.

can you guys guide me what option I should I choose or what should I do next? thanks

Your choice. I think you may even do both of you wanted too. Include more evidence.

Thanks mate,
any idea how long can take to get appeal date from first tier tribunal? what time frame is now a days? thanks

Get a DNA test evidence this will solve the time waiting for appeal and you can do both. Get DNA, apply for new application and also appeal. UKVI to my knowledge and experience are no longer accepting late birth registration only if you can proof that your father and mother are married before you were born, in this case its your mother very strange. DNA is the easiest and fasted evidence as advice by my MP if your parents are not married during the time you were born, this will stop the doubters who are the decision maker.

thank you very much guys for advice.

questione is now please
if I reapply are requirements are different now? because deadline date for EUSS family permit is over

only thing changed from my side is my wife eu national/sponcer have disability and my wife not fit to work anymore

2nd question is appeal easy to submit? can I do myself or have to hire solicitor

thank you

Since after the first July they changed the rules, they don’t presume evidence anymore. What evidence can be added?