Originally Posted by
Andro45
The way I did it (and I think that's the right way): make sure you have both beds and blankets ready, put Greta 1 in storage and then in the forge to warm up. Now place baby Greta 2 and grow to adult Greta 2 (don't collect Greta 1 from forge). When Greta 2 is grown, put her in the forge (in storage first). After that it's just a short wait and you can collect both Greta's.
I'm not sure if it's possible to collect Greta 1 from forge when Greta 2 is warming up, but I didn't take a chance and left them both in the forge until both were ready. No gems needed, because growing Greta will take about half an hour if you keep an eye on it.
Good luck.