Legal Assurance Letter Needed

I need a formal letter of assurance written by a legal person. A lady signed a blank will on behalf of the testator, without the testator present who claimed it was legal. The letter should confirm they did nothing wrong.

Requirements:
- Professional legal writing experience
- Knowledge of will and estate regulations
- Ability to convey legal concepts clearly and formally

The letter should:
- Be addressed to the friend
- Confirm the legality of their actions
- Use a formal tone throughout