There are two main issues here: (1) The survey sample : SMART concentrates on children aged between 6 and 69 months. If your KPC survey is investigating 'KP' (knowledge, practices) in carers of children aged 6 - 59 months then the two sample match. If your KPC survey is looking at 'C' coverage of programs for children aged 6 - 59 months and their carers (e.g. women of child-bearing age) then the two samples match. If your samples do not match than you could share the first stage sample and collect separate samples when in the selected communities. (2) Sample size : You can calculate the sample size using standard formulae and tools (e.g. SMART software). Remember to specify a design effect of at least 2.0 (unless you are really sure that you can go lower). I think you will find that the SMART survey sample size will be sufficient because this is calculate to provide a high precision estimate for GAM. Remember to leave time to collect the KPC data without rushing. You may want to use more smaller clusters. I hope this helps.

Thanks Mark for this reply, In practice, here are results of smart sample calculation : 455 children/ 539 HH/27 cluster, a 4% precision. while the standard KPC actually recommend 30 clusters / 10 HH and 10% precision. Is it acceptable to include all 0- 59 mths children to account calculation of exclusive Breastfeeding indicator and keep the 4% precision?

The issue here is that SMART uses a sample of children 6-59 months and EBF is from a sample of children aged < 6 months. There is no overlap. If you extend the SMARt sample to include 0-5 months then you'd have sample of about 455 * 1.11 = 506 and about 56 of those will be < 6 months. Estimating that indicator would yield a precision of about +/- 13% on a 50% prevalence (best case). I thunk you will have to use a dedicated sample for the IYCN indicators like EBF. How do others manage this? BTW : 4% precision is very high for coverage. EPI surveys, for example, aim at 10% precision.