Strong Affirmation:
* Acknowledge: To recognize or admit the existence or truth of something.
* Confirm: To verify or prove the truth of something.
* Endorse: To publicly support or approve of something.
* Sanction: To give official approval or permission to something.
Acceptance:
* Accept: To receive or agree to something willingly.
* Embrace: To welcome or accept something readily.
* Concede: To admit defeat or the truth of something reluctantly.
* Agree: To have the same opinion or to consent to something.
Other options:
* Assent: To express agreement, often by nodding or saying "yes".
* Approve: To officially authorize or agree to something.
* Grant: To give or allow something.
Let me know if you can provide more context about the situation you're writing about, and I can give you a more specific word recommendation.