Since it's for my father-in-law,
Then it is not recommended to sign and inscribe on it at will.
Because it may affect the future appreciation space of calligraphy and painting.
You can attach a holiday card or something, just write a few words.
If it is an ordinary finished calligraphy and painting,
Scratching may also affect the overall structure and aesthetic feeling.
Usually used for birthday themes,
It itself contains the meaning of blessing and auspiciousness.
For your reference,
You can always ask me questions.
I wish you a happy family!