Double pregnancy announcement

Ok so, yesterday was crazy! My sister came over to see my new house. We hardly ever see eachother, we've never really been close. I'm older by 3 years. So long story short, she tells me she is 10weeks pregnant! I kind of had a feeling she was going to tell me this, as she wouldn't normally have come over. But! Plot twist! I tell her congratulations... And that I'm actually 5 weeks pregnant! I found out 3 days before, and have been trying for 5 years! She cried and hugged me she was so happy! So now we just need to think of a way to tell our mum! She will be super excited, she really wants grandchildren and after my miscarriage two years ago, I don't think she will expect it, and certainly not from my sister, who is the least maternal person you could get 😂😂

Any ideas or tips on a cool way we could reveal? My mum and I are close and it's killing me not telling her, but my sister and I want to tell her together 💖💙