Her eldest, Holly is at Newcastle uni, younger daughter Tilly has just turned 18 in September so could be still in 6th form. The Sun article' wording was quite clever
" They held Zoom meetings with both parents, who cannot be named for legal reasons, "
This suggests the parents are not together, either physically or in a relationship with each other which would fit Davina.
There are very few images of Davina with her so not easy to identify but a Tilly Robertson has a youtube channel and from some of the vids you can identify the boarding school she attends if you look closely. She also has a video of visiting her sister at Newcastle uni so very likely to be the same person. Sloppy Sun reporting as the fees are nearer £40k a year boarding not £20k!