Lily's protection worked differently, so Harry could be raised in the wizarding world instead of with the Dursleys. He's raised by the Tonks family as a son, and a brother. Ted and Nymphadora die anyway.
Andromeda knew what'd happened the moment she laid her eyes upon Harry - her seventeen year old son whom she never birthed, who's long hair curled in a manner so similar to her own. Harry had never been a crier - he'd become teary eyed, and perhaps the tears would fall, but he wouldn't weep.
And so, when he appeared in their front door - still filthy from the battle she hadn't been part of, to care for her grandson - with his stomach spasming in weak, silent sobs, Andromeda knew what'd happened. When he stood in the doorway, eyes wide and haunted and overflowing with tears like two waterfalls, Andromeda began to shake.
When his haunted expression met hers, and his eyes glanced around the living room where they'd made all their best memories, Andromeda began to cry, too.
"M-Mum..." Harry whispered, jaw shaking. His eyes kept flitting between her and little Teddy, between Ted's armchair and Nymphadora's spot in front of the fireplace. "M-Mum, they're- they're all- they-"
Harry fell to his knees, and if Andromeda hadn't been holding Teddy, she didn't know what her body would've wound up doing. She wanted to scream and rage, she wanted to throw things and destroy, she wanted to curl into a ball and run forward and embrace her son - but she couldn't. Teddy wasn't even a month old.
Andromeda was too weak to stand as her vision blurred beyond recognition. She was hardly aware of Teddy's cries - not when Harry wailed for the first time in his life. Not when she knew the three of them in that room were all that remained of their family.