Peel peaches if desired. See note below on how to blanch peaches to easily peel them.
Remove the pit from peaches. Finely chop the peaches, mash them with a potato masher or lightly pulse in a food processor.
If making Freezer Peach Marmalade, remove seeds from the orange and slice into thin strips or triangles. Add the orange pieces and lemon juice to the peaches and stir in sugar. Let stand 10 to 15 minutes, stirring occasionally.
Meanwhile, combine powdered pectin and water in a small saucepan, stirring constantly. Bring to a boil over medium heat, stirring constantly. Boil 1 minute.
Gradually add pectin to peach mixture, stirring well. Stir gently about 3 minutes or until sugar is almost all dissolved.
Spoon peach mixture into plastic or glass 1-cup freezer jars or containers. Wipe rims and cover with lids.
Let stand at room temperature overnight. Store in freezer up to 1 year. Thaw in refrigerator overnight. Store in refrigerator up to 3 weeks.