She was devastated and it's only been the last few weeks she's stopped asking about him.
Too much of a risk to even think about birthday contact when she's literally only just getting over not seeing him for so long - too soon. I think she'd find the suddent reappearance and 'Happy Birthday darling!!' like FUCK ALL HAPPENED just as traumatising, if not more. Don't do it to her on her birthday, really.
Friend has had this. Dad is overseas but what the kids struggle with most isn't him being gone, it's when he pops up and is Mr Cheery 'Love Ya!' dad who brushes off their questions about why he hasn't called for six months and why he never replied to their texts, oooh well I was busy but HEY look at this amaaaazing thing I'm just about to send you to make up for it!' Utterly awful for them. She wishes now she'd just cut contact.
Look, he has SHOWN how much he gives a shit - he doesn't. You cannot make him be a good dad, you can give all the warnings you like but you KNOW from his actions that deep down he does not care about this little girl, not like a parent should. So yep he will probably do the same thing again in a few months, or maybe a year, because he's shown when the chips are down that it doesn't take much to push her off the bottom of the list of important things. Do you really think he's going to listen to your warnings and totally change, or even give your threats any weight?! He will have at the back of his mind the idea that 'She's my daughter too, her mum can't dictate to me anyway.'
I don't know exactly what reply I would send now but I would be very clear just how traumatising your DD has found the last few months and how hard it has been for her to process the fact that her dad has abandoned her. I would be 100% clear that NO FUCKING WAY is he popping up on her birthday - that she would find that utterly upsetting and you're sure he doesn't want to be faced with a hysterical child screaming questions at him in a situation like that. No. Way.
If he wants to restart contact it is going to have to be slowly, carefully and he had better be prepared to have some very good, age-appropriate answers for his daughter on why he ghosted her. It won't be for her birthday. He needs to tell you what his plans are for contact so you can start introducing the idea of him returning and gauge how she feels. Suggest counselling. Oh and tell him you will also be going to CMS as you too could do with a less traumatic, more formalised set of arrangements going forward now you've seen exactly how little he can be trusted to b a parent.
If he doesn't agree to the timeline and suggestions you propose then he can just take it to court as you won't be compromising one inch. He'll then see DD once a court order has been finalised and not one second before.
Basically what all that will do is give him a massive wake up call as to exactly what the effect of his actions have been and how seriously you're taking it. And... he will either wake up, OR he will think 'Oh fuck that' - and then you will know where you stand.
Have to say I think it will be the latter, and then you'll save you and your DD a whole shed load of more trauma.
Men like this fucking stink. He will be no loss to her.