unexpected pregnancy, how to tell boyfriends family

we are 29 & 27 years old. both with good jobs health benefits. i have 2 daughters 8&5 from previous relationship. i have been in a relationship with my current boyfriend for 3 years- we just found out we are having a baby unexpectedly and don’t know how to tell his family. they are super religious but also very open to accepting me and my daughters. basically whatever makes their son happy they accept- but we are super nervous to tell his family... we currently rent a larger home and do have the space for one more... when and how should we announce ?!

we are so scared !