My husband and son make custom outdoor furniture. A friend has requested a version of these chairs for an elderly parent. We would be glad to do so, if we could find information on what those alterations should be. One of the examples we were told was that the chair seat/back angle needs to be adjusted so that it "holds" a person better. What should (or shouldn't) those angles be? Can anyone point me to any references (printed, on-line, personal, other) about the ergonomic criteria or specifications for geriatric furniture? Thanks.