Rumer Willis Shares Bruce Willis and Demi Moore's Excitement as She Prepares to Welcome First Grandchild

Rumer Willis says her parents are "so excited" to become grandparents.

Speaking in this week's issue of PEOPLE about her partnership with NakedCashmere on a capsule collection for mothers and newborns ahead of Mother's Day, the mom-to-be — the oldest of Bruce Willis and Demi Moore's three daughters — shares that she is thrilled to kick off the family's next generation.

"[My parents] are so excited. My sisters are so excited, and it's so fun to be bringing in the first grandkid in our family, especially because we're such a huge group at this point," she tells PEOPLE.

The pregnant actress, 34, says her first pregnancy has been "humbling" so far.

"I have so much reverence and respect for women now. I feel I've had an easier time physically than most of my friends," the Once Upon a Time ... in Hollywood actress adds.

"Also, because I'm so excited, even those moments that are challenging, or feel frustrating, I'm just so excited, that always kind of trumps [everything]... But, it's wild. It's the wildest experience, even more so than I ever thought of."

When it comes to getting parenting advice, Rumer has a wealth of knowledge close to home from the Die Hard actor, 68, and the G.I. Jane actress, 60.

The best advice they've shared so far? "You have no control over anything, and just have a lot of grace with yourself," Willis says.

Also giving Willis plenty of grace is boyfriend Derek Richard Thomas, whom she celebrates as "an angel" throughout her pregnancy.

"He's been so lovely, and he's just so excited to be a dad, and we're both just so delighted to meet whoever this little person is," she shares. "I could not have asked for a better partner, and he's going to be such a great dad."

"I just can't wait to meet them," Willis says of her little one. "I'm just so delighted. I feel sometimes I can just feel the energy of this kid sometimes, and I just can't wait to hear them laugh, to figure out who they are, play with them and get to know them."