United Kingdom, May 14 -- Domino Kirke and Penn Badgley are staying "very fluid" with their preparation for twins.

The 'Teething' singer - who already has 16-year-old son Cassius with ex Morgan O'Kane and a four-year-old son James with the 'You' actor - has revealed how her family are preparing for the new arrivals.

She told E! News: "Everyone is in the same boat, very, very fluid with it.

"I think they're taking my lead. No one's holding on too tight. It's just an expansion-that's what we're here for."

Domino - who announced her pregnancy two months ago - admitted the idea of welcoming twin baby boys is "so overwhelming".

She said: "It's humbling. It's so overwhelming. The idea of two at once, it's one of those things where you just...