In Baguaquan the Crotch kick 撩陰 (liāo yīn) is a short kick, therefore the body is kept straight. There are styles where similar kick is to more far, see the video for explanation / demonstration.
The back keep relaxed (remember not collapsed) and use the jins at the back of the leg.
After the kick only the knee relaxed, the hip joint not, so the leg is not lowering, this way the next kick can start from that position.
Lets see the 3 kick combination.
Side kick kick 踹腿 ( chuài tuǐ )
hook step 扣步 ( kòu bù )
closing dawn 貼襠 ( tiē dāng )
back kick with heel 後蹬 ( hòu dēng )
Crotch kick 撩陰 ( liāo yīn )
he ten steps form 實步拳的十步 (Shí bù quán de shí bù).
Five steps forward and five steps backward
The first two movements and possible application of it
The right force takes to the next movements, use the spiral force here as well
More details at the day videos search like https://www.youtube.com/results?search_query=%E3%80%90%E5%85%AB%E5%8D%A6%E7%9B%A4%E9%BE%8D%E3%80%91%E3%80%9020191214%2808%29%E3%80%91
HeJingHan BaguaQuan, Baguazhang Teaching Taipei.
See more videos at Youtube playlists
some materials could be added from HeJingHan book:
Bagua Quan Foundation Training