the result of bopsection(BRepAlgoAPI_Section)

Dear everyone.

Tried Draw Test;

pload ALL

stepread SectionTest.step"attached file" com
Mode (0 End, 1 root n0 1, 2 one root/n0, 3 one entity/n0, 4 Selection) : 1
Mode (0 End, 1 root n0 1, 2 one root/n0, 3 one entity/n0, 4 Selection) : 0

explode com_1

section so com_1_1 com_1_2
explode so
lprops so_1 "Mass : 1.35"
lprops so_2 "Mass : 0.00162529"

bop com_1_1 com_1_2
bopsection sn
explode sn
lprops sn_1 "Mass : 4.26363"
lprops sn_2 "Mass : 1.35"

I want three edges (sn_1, sn_2, so_2) at the result of bopsection (BRepAlgoAPI_Section).
Even if it gives two edges(sn_1, sn_2) BRepFeat_SplitShape, it is because the split of com_1_1 goes wrong.
If three edges is given to BRepFeat_SplitShape, the split of com_1_1 will be successful.

How to get the result that I want?

Regards.