If any individual or organisation thinks there is such a huge safeguarding risk about parents being informed about any aspect of their child's life that they will keep that information secret then it is quite clear in safeguarding legislation, the procedure for removing the children from their parents should be started.
Parents being uncomfortable about / unaccepting of a child's sexuality or identity is not a sufficient reason to withold safeguarding information from them as primary safeguarders (unless there is credible, tangible evidence they will physically seriously harm the child as a result - in which case remove the child).
It's quite clear in the Children's Act that parents are the primary adults responsible for safeguarding, not the school / religious leaders or whoever else. The threshold for witholding information from parents is incredibly high and is essentially at the point where social services should be intervening and removing the child.
Adults cannot say 'it's too much of a safeguarding risk to disclose but they can stay living at home'. No, those other so say 'responsible' adults are themselves committing abuse in this case as they are forcing children to live a double life, the mental consequences of which could be severe, and witholding vital information from those primarily responsible for their safeguarding, which could result in terrible consequences.
A key foundation of safeguarding is information sharing.
Anyone suggesting this pile of rubbish about secret keeping doesn't understand safeguarding or is seeking to undermine it. They're creating exactly the sort of situation - for ideological reasons - that lead to the several serious case reviews we've seen. Keeping secrets will not help the child except where they should be removed anyway.