Authorization Letter for Son

I need a formal letter authorizing my son to act on my behalf. He will need to engage with various organizations, both public and private, in my best interest.

The letter should grant him access to:
- Medical records (HSE)
- Communication records (Three Mobile Ireland)
- Engage with solicitors on my behalf (including retaining solicitors)

The letter should also mention:
- Tusla (Child and Family Agency)
- Public and private agencies

If there are any additional entities needed, I would appreciate your guidance.

Ideal skills and experience:
- Legal writing expertise
- Experience with authorization letters
- Familiarity with the mentioned organizations