How to surprise bf and daughter

Dulce ā€¢ I`m 24 yrs old and I`ve been with my boyfriend for 8 years . We have a 4 yr old princess šŸ˜Š
I took a pregnancy test and it's positive šŸ˜Š my daughter bday is around the corner and would love to surprise them . Any ideas on surprising them ? I was think a shirt to my daughter saying big sister .Ā