All three should be Potanthus omaha.
1. male 2 & 3 are females.
It is very difficult to ID Potanthus based on one view.
At least an upperside or underside HW should be visible.
No 3 have the abdominal end black but it is due to excessive wear.
Three species in Singapore have the abdominal end yellow with a thin black line/band basally.
They are P. ganda, omaha & confucius.
P. omaha ;Duller yellow brown.
Veins more noticeably darkened especially acorss the HW band on both sides.
Males.
http://www.butterflycircle.com/check...obby%20Mun.jpg
http://www.butterflycircle.com/check...20Tan%20CP.jpg
Female. Note female always have some darker shadings on the abdominal end.
http://2.bp.blogspot.com/-haPCSiByxe...0/DSC_0188.JPG
P. ganda; deeper orange; Veins across the HW band on both side not darken or lightly so.
Underside HW more heavily dark shaded than in P. omaha.
Males
https://farm2.staticflickr.com/1337/...ac5c42d89d.jpg
https://i1.wp.com/www.singaporegeogr...rt-1.jpg?ssl=1
Female.
http://www.butterflycircle.com/check...t_Adult_02.jpg
P. confucius . Veins not darken
FW band in the male with a continuous undivided appearance. All spots overlapping.
Underside band edged with darkish spots but may also be very lightly marked.
Males Thailand.
https://www.thaibutterflies.com/wp-c...s-1080x717.jpg
http://lh6.ggpht.com/oqIZdT5RbncTEu9...SP5vZ2Hf_=s600
Males Singapore.
http://3.bp.blogspot.com/-B2W0fVicLA...-confucius.jpg
https://inaturalist-open-data.s3.ama...jpg?1623329984
TL Seow; Cheers.