"As we can see Khufu is clearly depicted as a female"
The children depicted are those of Seneb, and are honorary names to his regents. This is not a female Khufu (pharaoh). Also note there are actually 3 names written. It is thought the third child is not depicted in relief because of being stillborn, but this is speculation on why the child is not there. See Veronique Dasen "Dwarfs in Ancient Egypt and Greece", p.127.
You wrote:"the lines in the circle are obviously not meant to represent the "kh" in "Khufu" and could not be one and the same as a sieve despite appearances. No other pharaoh required this not even KHafre"
The lines themselves are not the 'kh' phone, per se, rather the complete glyph Aa1 is. Whether in actuality a sieve or placenta is depicted is still inconclusive (note Gardiner's '?', Egyptian Grammar p.539) but we can be fairly sure of the phonetic value (review ibid p.583-586). For your interest, Aa1 has an associative phone of 'sh' through F32 (animal belly) as the latter is seen substituted for N37 (pool). We can therefore appreciate how Khufu might have ended up as Shufu / Suphis.
As regards Khafre, his name is not written with Aa1, rather N28 'Kha' ('rising sun' glyph), so not comparable with Khufu.