I understand that minipill is not licensed for hrt because it is a contraceptive and usually not a high enough dose (it is the lowest dose between POP, hrt and the COCpill). Cerezette is a bigger dose and I have seen opinions written in forums for gps that it might be enough progestogen on its own, so should be licensed.........but it isn't atm.
Because hrt is not a contraceptive, some GPs put the two together (although I have not seen many posts about that it a while)
Two a day seems quite a lot, but I don't think it should do any harm if you do not have a problem with it. The extra femoston is a sequential one, so you will have 14 days with more progestogen and 14 days without. 1/10 is low dose, so has probably minimal effect.
However, all this layering seems a bit of a faff and unnecessary. I think my bowels would be permanently on strike with all that progestogen

I would have thought it would be far better to have a mirena, then add the oestrogen with a gel or patch as that should give you the no-bleed, you will have enough progestogen in the right place for the hrt and contraception, all with the minimum amount of progestogen to do the job. You would then be ok for the next 4 years, and could tailor your oestrogen dose to suit.