Toddler Is Peeing and Pooping on the Floor

If there really isn't anything else going on, and it's just a phase or attention-seeking behavior, then I would start making HER clean up the messes she makes. Remind her that she needs to use the potty like a big girl and if she can't do that, she will need to clean up her own mess (with adult supervision and help, of course). Hopefully she will find it icky enough that she won't want to continue.

I'm not expert at all. But if the problem is actually happening at the mom's house, it seems to me that the problem is more likely centered there, if it's enviromental/parenting related.

It would be best to get her checked by the pediatrician, but it sort of sounds like the potty training could be a control issue (or for attention) between the mom and your daughter. Or, that the mom is not being proactive by reminding her to go/taking her to the bathroom at regular intervals.

Don't let the mom blame you for this though: if she were having a problem at your place or in somehow related to your house or the parenting there, I seriously doubt she'd hold all that distress inside (no pun intended!) and let it go at Mom's--most 4yos don't have that much forethought.

I agree with DVMMOM-both parents should be unemotional about it, and have her help clean up the messes; it's part of the natural consequences to the action. One other mom (in a similar post) recommended a cold shower/wash off in the tub, or making the child help wash the underwear out in the cold water (it's unpleasant but doesn't hurt).

Hmmm...who knows why kids do what they do sometimes but having said that it seems more logical that this is caused by something going on between your daughter and her mother.

I agree with others that it could be due to different levels of attention she is receiving at one house vs the other; or just simply testing boundaries/limits with Mom.

In any case, blame won't solve the issue so I'd talk with your ex about a strategy on how to handle the situation. I wouldn't make a big deal about the mess but your daughter should help clean (herself and the area where she soiled) and she is old enough to change her clothes (if necessary) and help do any laundry associated with the mess. As another posted, you could try to casually work the topic into a conversation to hear your daughter's side of the story.

I watch little ones quite a bit and I am always very carful that they don't learn undesirable behaviors at my house and take them home. If she were going on your floor at your house and then began to do it at her Mom's, I would think you had a part to play, but it really seems like this is something between her and her Mom. A 4 year old has a pretty good vocabulary. You both could just kind of work it into the conversation to see what the little thing has to say. I would be careful how I do it because if she feels she may get in trouble, she may not tell you. Four year olds pretty much tell everything. My guess is that it is a bit of testing of the rules with her Mother. I often encourage the children I care for to be better with their parents. You could do that with your daughter.

If she is doing this on purpose then it could be to get attention or because of stress of some kind. It is also worth having a docrtor's check up just in case there is a bladder infection or something (I had a really bad one around that age, no one realized what it was until I was sick with a fever). But then again my son is 4.5 (potty trained about a year) and still does much better when he gets regular reminders to go to the bathroom every few hours (he usually says he doesn't have to go but nearly always does). If I let him just go when he wants/remembers he often wets a tiny bit before he gets to the bathroom. At least it is an easy thing to try.

As I read through your post I had a few thoughts:
1. If it is only happenning at Mom's then it is probably an issue with Mom, not you.
2. This could just be a phase.
3. Maybe she is getting too much attention at your place and feeling ignored at Mom's. Kids don't care if the attention they get is negative or positive, as long as they are getting it.
4. Some kids will regress with potty training when they are being sexually aboused...probably not the case but wanted to make sure you are aware.
Good luck!