I've read your posts, thanks - you asked tonight, in this manner, for suggestions:
I'm sure that you're rightly defensive because you are, indeed, perfect teachers. Since you're so brilliant at what you do, perhaps you'd kindly respond to the OP's question: Do you 'have any ideas of useful websites/ workbooks etc. which could help' their child to achieve L6 in English.
Other posters have come up trumps, recommending textbooks and books to read. There followed a useful discussion on the difficulty of finding appropriate texts for very able readers without age appropriate content.
You only responded on Sunday evening with a link to last years SPAG (that's not reading, btw) - which you presumably know as an advisor would be unhelpful for parents to use even for writing. That isn't what the OP asked for. You also gave some level descriptors for reading.
If I was as unkind, I could possibly phrase it as 'I'm sure that you're rightly defensive because you are, indeed, a perfect advisor. Since you're so brilliant at what you do, perhaps you'd kindly respond to the OP's question: Do you 'have any ideas of useful websites/ workbooks etc. which could help' their child to achieve L6 in English?*
I'm guessing you don't, then? 