Parenting question

[Familyman5]

Hi first time posting and hoping for some advice. I have older children who are now adults, I then met my now partner when she had a 6 month child. Dad was not involved. Fast forward nearly 8 years later and she calls me dad and knows no different. I have cared for her, provided for her and brought her up as my own. The biological father has now decided he wants access to our daughter, he is on the birth certificate. He is threatening the legal route, he has also stated in writing that the reason for his absence was alcohol. As she doesn't know him we have declined which has led to all kinds of abuse directed towards me and my partner. We have kept all of this as evidence. Rather thank show any gratitude that I have brought her up and provided for her he has threatened me, I have not replied to any of the messages. Just wondered if anyone has any advice?

I never understand why someone who is essentially a sperm donor suddenly decides they want to be in touch with their ‘child’ out of the blue.

Is he likely to follow through or get bored? If he will follow through then start the court process, and if he won’t then ignore him until he disappears.

UNLESS having him in her life will benefit her, to be fair at age 8 I wouldn’t be forcing anything on her and I would be asking her how she feels about it, but very carefully.

I don't really know what to say, he is now posting pictures on social media of her taken from someone else's profile but with my biological daughter in. I have reported but seems he is getting desperate.