Cut 1 lb. Meyer lemons and regular lemons lengthwise into quarters, and place in a 6-qt. stainless steel or enameled Dutch oven. Add 3 cups water. Bring to a boil; reduce heat, and simmer, uncovered, 1 hour and 30 minutes or until lemons are very soft and liquid is syrupy, pressing lemons to release juice. Remove from heat, cover, and let stand at room temperature overnight.

While quartered lemons are simmering, quarter remaining Meyer lemons lengthwise; remove seeds, and cut crosswise into very thin slices. Place in a 6-qt. stainless steel or enameled Dutch oven. Add remaining water (just enough to cover lemon slices). Bring to a boil; reduce heat, and simmer, uncovered, 30 minutes, stirring occasionally. Remove from heat; cover and let stand at room temperature overnight.

Prepare boiling water canner. Heat jars in simmering water until ready for use. Do not boil. Wash lids in warm soapy water and set bands aside.

Pour lemon quarters mixture through a fine-mesh strainer into Dutch oven containing lemon slices, pressing with back of a wooden spoon to extract as much juice as possible. Discard solids. Add sugar and lemon juice to lemon slices. Bring to a rolling boil over high heat; reduce heat to medium, and cook, uncovered, stirring often, 45 minutes or to gelling point.

Ladle hot marmalade into a hot jar, leaving 1⁄4-inch headspace. Remove air bubbles. Wipe jar rim. Center lid on jar. Apply band, and adjust to fingertip-tight. Place jar in boiling- water canner. Repeat until all jars are filled.

Process jars 10 minutes, adjusting for altitude. Turn off heat, remove lid, let jars stand 5 minutes. Remove jars and cool 12-24 hours. Check lids for seal, they should not flex when center is pressed.