HOW TO CROSSBREED ORANGE AND GRAPEFRUIT

Question

PURCHASED A HOME WITH ORANGE/GRAPEFRUIT TREE IN BACK YARD. WE WOULD LIKE TO KNOW HOW TO GROW ANOTHER TREE. WE LIVE IN hOUSTON

Answer 1

It should be possible to cross-pollinate an orange with a grapefruit and produce seeds, because the grapefruit is itself a hybrid of an orange and a pomelo. Follow these instructions to hand-pollinate the trees:
https://www.gardeningknowhow.com/edible/fruits/grapefruit/hand-pollinating-grapefruits.htm
https://www.gardeningknowhow.com/edible/fruits/oranges/hand-pollinating-oranges.htm

You may also need to take measures to prevent the cross-pollinated flowers from beig pollinated by flowers on the same tree. The resulting fruit should be the same as the parent plants' fruit, but the seeds will be genetically different, and should produce a tree with different fruit if you plant them.