Calculating MOEs from derived ACS estimates

I have a question. I asked the Census Bureau how to calculate margin of error when aggregating groups.

The Compass for Understanding the ACS: What researchers need to know, says on page A-14, says to sum the squares of MOEs for each sub population. Then the square root is the MOE of the aggregation of the subgroups.
www.census.gov/.../

However, I tried that with this table for New York State: B17024, AGE BY RATIO OF INCOME TO POVERTY LEVEL IN THE PAST 12 MONTHS. Universe: Population for whom poverty status is determined. 2009-2011 American Community Survey 3-Year Estimates.

According to the table, the MOE for children under 6 is 4,562. But if I do the calculations using the MOEs for each income subgroups, the calculated MOE that I come up with is 13,002, which is more than twice as large as the stated MOE for total 6 year olds.

I contacted the Census Bureau and they replied "The method in the Compass Products is an approximation method for calculating MOE. The formula provided (taking the square root of the sum of the squares) does not incorporate the covariance between each term. This can lead to the approximation diverging from the the true MOE, which you saw when you created your approximate MOE."

The person I talked to also indicated that there are no covariances available for the public to calculate actual MOEs.

So I was wondering whether the web sites above use the Compas formulas, and how they might account for the covariances?

I have a question. I asked the Census Bureau how to calculate margin of error when aggregating groups.

The Compass for Understanding the ACS: What researchers need to know, says on page A-14, says to sum the squares of MOEs for each sub population. Then the square root is the MOE of the aggregation of the subgroups.
www.census.gov/.../

However, I tried that with this table for New York State: B17024, AGE BY RATIO OF INCOME TO POVERTY LEVEL IN THE PAST 12 MONTHS. Universe: Population for whom poverty status is determined. 2009-2011 American Community Survey 3-Year Estimates.

According to the table, the MOE for children under 6 is 4,562. But if I do the calculations using the MOEs for each income subgroups, the calculated MOE that I come up with is 13,002, which is more than twice as large as the stated MOE for total 6 year olds.

I contacted the Census Bureau and they replied "The method in the Compass Products is an approximation method for calculating MOE. The formula provided (taking the square root of the sum of the squares) does not incorporate the covariance between each term. This can lead to the approximation diverging from the the true MOE, which you saw when you created your approximate MOE."

The person I talked to also indicated that there are no covariances available for the public to calculate actual MOEs.

So I was wondering whether the web sites above use the Compas formulas, and how they might account for the covariances?