Someone mentioned this in group a while ago and our c said that this isn't following the plan 100%. the reason being was due to the fact that different types of HE are not the same, eg milk is very different to cheese. Or something like that, can't remember the exact details of why it was just it shouldn't be done.
I think it was the case that you never used to be able to split your HEX's because you may not be getting the full calcium or fibre allowance, but I am sure it is in the slimming world FAQ online that you can now do this. (perhaps someone will check). I know many people do anyway.
I have looked online and you can split the healthy extras that are in two parts. Eg you can have the cereal in the morning and the scan bran for lunch. I haven't found anywhere about only having 2 halves of a portion eg, 1/2 of 28g cheese and then 1/2 a portion of milk.
Yes it was definitely in the FAQs on the SW that you could split your HE as long as there was only one food listed for the HE. So bread is fine but not porridge because the HEB is suppose to be porridge + scan bran