Hello , my twin boys are 3.6yrs old with 15.4kg,14.9kg wt and 104cm,102cm height. They are very active and eats ok,but they look lean. Our biggest concern is about their sun exposure which is Equalent to zero due to this pandamic. So we are very much worried about their food absorption and d3 deficiency along with growth overall due to limited mobility( although they keep running and jumping in our decently big flat) . Please suggest which multivitamin and d3 can we giv and dosage ( along with IU and Ml) as there are many drops and syrups in the market and it's confusing. Thanks .