dear parents this is a concern for majority of parents at or around your stage. dufalc is not a parmanent solution. you have written about banana what about rest of the diet. since its chronic now it will take long.
add ladies finger, guava, papaya, in her regular diet.
take her to a surgeon and check out for
anal fissure. as she might have one or two and that could well be the cause of not passing stools completely.
stop any chilly or papper for the time being.
spend some time with her and listen to her.
while offering her fruits n salds have it yourself too.
have one meal together and share your experiences and listen to her.
give her a cup of milk with honey and a tsf of ghee before bedtime. make a habit of having a big glass of warm water as soon as she wakes up, this will cause better intestinal motility.
indulge her in some sports or exercise activity and you too do it or something sporty with her.
regularise her and your life, because defecation reflex has its own time and one should be up before it or it is postponed for maybe 24 hours, further adding to the problem.