Sounds alot like my crazy ex bf. I finally left because I refused to subject my daughter to his toxicity.

Once his obsession with me fizzled out, he forgot my daughter existed and has maybe asked to see her 5 times in as many years.

Her comunicating with him is feeding his obsession for her big time. She needs to cut that shyt out. NOW.
This isn't a game and if she's not willing to cut him off, I suggest she take the drama elsewhere.

Because what you have described, I've been there, that isn't love, she is inlove with the idea of him. Not the reality of him, and if she is willing to settle for that, that is her choice, but her poor unborn baby has no say in the circumstances into which s/he will be born. So if he is what your daughter chooses, she needs to really think twice about being a mother because she won't be putting her baby first at all.

When he finds her, you and your bf will be obstacles, so your daughter needs to make her choice, before he comes to claim "what's his" and tramples on any obstacles standing in his way.