Beyonce and Jay Z's daughter Blue Ivy is a ''very good'' big sister to their twins.

The 'Formation' singer and her 47-year-old husband welcomed their little ones into the world at the beginning of last month and, although Blue has had her parents all to herself for the past five years, she's adjusted well to the family's new arrivals.

Beyonce's mother Tina Knowles told 'Entertainment Tonight': ''She's [Blue is] very proud and excited. She's a good big sister, she really is.''She cares for them a lot.''

The internet went wild earlier this week when the 35-year-old singer took to her Instagram account to reveal an image of herself cradling the one-month-old youngsters and revealed that she and Jay had named them Sir Carter and Rumi.

She wrote: ''Sir Carter and Rumi 1 month today. (sic)''

Although eyebrows were raised over the pair's choice of name for their babies, Tina has admitted the reason behind the monikers will be revealed in due course.

Beyonce's latest post comes after Jay admitted earlier this week that his marriage ''wasn't totally built on 100 per cent truth''.

The 'Empire State of Mind' hitmaker - who married the brunette beauty nine years ago - admitted the ''hardest thing'' he's ever done is having to face up to potential difficulties in his union and try to work them out.

He said: ''This is my real life. I just ran into this place and we built this big, beautiful mansion of a relationship that wasn't totally built on the 100 per cent truth and it starts cracking. Things start happening that the public can see.

''Then we had to get to a point of, 'OK, tear this down and let's start from the beginning ... It's the hardest thing I've ever done.''

Jay's new '4:44' album features an apology from him to Beyonce, and speculation is rife that it is a direct reference to claims she hinted to him being unfaithful with ''Becky with the good hair'' on her visual LP 'Lemonade'.

In another song he also appears to reference the infamous Met Gala 2014 incident in which he was attacked in a lift by sister-in-law Solange Knowles.

He raps: ''You egged Solange on, knowing all along all you had to say you was wrong.''