Once upon a time there were three kids. Oldest, Middle and Youngest. All three of these kids shared their parents bed from birth until they wanted to sleep in a bed of their own. The three kids parents knew that co-sleeping was safe if you followed some guidelines and so so good for both the parents and the kids so they were happy to co-sleep for as long as all parties were happy. And the parents of the three kids did love having their babies close.
But it wasn't all smooth sailing.
Oldest was too cuddly. As she grew she spent all night being a barnacle on her Mama's back and not letting there be more than 1 centimeter of space between them at any given time. But the Mama got used to it and soon was sleeping soundly with a small person suctioned to her back.
Middle was too pointy. As she grew she slept in the shape of a greater than sign and you either got the pointy bum or the pinchy toes poking you all night. But the parents got used to it and soon all slept soundly with with a blanket tucked between them.
But Youngest was just right. As she grew she slept still and sound and snuggled in a ball without pinching or poking or sticking herself to either of the parents. And the parents were happy and everyone got lots of sleep.
As the years passed Oldest grew and wanted her own room so the parents made her one and she slept in there happily. After more time passed Middle did too and the parents realized that those years with their babies and children co-sleeping was coming to an end. They were both sad that those magic years with small kids had flown so fast and happy because they knew that one day they would get back the whole bedroom to themselves. And also optimistic that the magical and elusive "regular sex life" might return under the right conditions.
But until that day they were happy to share their room with youngest (who now sleeps in a bed of her own right next to the parents bed) and whenever she wanted to climb in-between the parents and sleep they were happy to let her. Not only because they knew that soon she would be too old to share the bed and they would be sad that their last baby was a baby no longer, but also because she wasn't too cuddly or too pointy but she was just right.