Regarding the management of malnutrition in children over 6 months:
I presume that the question is referring to the stabilisation phase of malnutrition. Generally speaking, the use of diluted formulas seems anecdote-based, rather than evidence based. I can't find any evidence supporting using diluted formula, although this might be because each formula has different levels of protein and electrolytes, and guidelines might not want be seen to be supporting one brand of infant formula above another.
F75 has low protein / lower electrolytes than either diluted F100 or infant formula.
The issues with using either diluted F100 or infant formula in the stabilisation phase is that it may inadvertently increase the risks of diarrhoea (due to altered electrolytes) or refeeding syndrome (which may get mistaken for sepsis or heart failure) in these acutely sick children. The higher protein load may also exacerbate existing renal failure. The other issue that the children (especially those with Kwash) are on the borderline for fluid overload / heart failure so giving them too much fluid may push them into heart failure.
1) Firstly the WHO guidelines:
http://www.who.int/nutrition/publications/severemalnutrition/9241545119/en/index.html
Section 4.5 explains the nutritional values of F75 and how to make up solutions if you don't have the prepared powdered F75.
The following references are pretty much the same:
2)
http://www.ncbi.nlm.nih.gov/books/NBK154454/
Section 7.4.8 shows the breakdown of what is in each type of formula used, and how to make up alternative formulas.
3)
https://www.lshtm.ac.uk/eph/dph/research/nutrition/improving_inpatient_treatment_of_severe_malnutrition.pdf
This guideline is clear on the different electrolyte levels, check Appendix 2
4) There are some sites that suggest alternative recipes depending on what is available:
http://motherchildnutrition.org/malnutrition-management/info/feeding-formulas-f75-f100.html
I would recommend either using F75 or making up replacement feeds to the above specifications only. Breastfeeding in addition would be good. In general, as these kids stabilise, their appetites return. That is when I would consider a slow switch to F100 (rehab phase). You have to be more careful in the ones with oedema and you go by the transition phase first.
This article is interesting, from the end of page 671, as it explains why F75 is important:
http://www.ncbi.nlm.nih.gov/pubmed/20972284
In addition:
In the management of diarrhoea (rehydration), they should use ReSoMal rather than ORS.
If they are using formula and the child has diarrhoea, zinc should be added. If they are using F75/F100/RUTF, these contain zinc so no zinc supplement should be added.
In the question of infants <6months, this is what the WHO recommends:
http://www.ncbi.nlm.nih.gov/books/NBK154454/
“-For infants with severe acute malnutrition and oedema, give infant formula or F-75 or diluted F-100 (add water to formula in recipes up to 1.5 litres instead of 1 litre) to supplement breastfeeding.
- For infants with severe acute malnutrition with no oedema, give expressed breast milk; and when not possible, commercial infant formula or F-75 or diluted F-100, in this order of preference.”
I haven't found recommendations for diluting formula in these cases.