Be aware that there are no guarantees that ANY of you will get aid in those proportions,
When you fill out the FAFSA, the parent's portion of the EFC will be 1/2 the usual number when there are two kids in college.. 1/4 when all four of you are in college. However, that is the FAFSA EFC which only is a marker for qualifying for federal and some state aid in terms of what is guaranteed. The cut off for PELL is an EFC of about $6K so even with four kids, getting much that way is not that easy. Eligiblilty for unsubsidized Staffords do not depend on income.
Colleges that use just FAFSA do not tend to meet 100% of need, so in some cases it won't matter how low your EFC is, if the colleges chosen to do not give out the money. It does make it possible to get more money since you have the EFC to justify it, but it, by no means, guarantees it.
Those schools that tend to guarantee to meet need are not as generaous with what they feel is the parental contribution and will tend to take 60% of what the parent is expected to pay for one child rather than half. They also tend to be more selective in admissions as well.
Does your brother go to a school that meets full need?