Is your daughter OK about the visitation during the daytime hours? Is the overnight aspect the only reluctance she displays? Does she describe any particular worry when she is emotionally upset or at other times? Or is the reluctance more vague and general in nature? When she is not upset, talk with her about her worry and see what she has to say. Likely it represents missing her mother and not any other particular concern, but it's good not to assume that.
My daughter seems fine with the day time visitation, it is only staying the night that upsets her. I have asked her about it and she is rather vague, all she says is she only wants to sleep at Mommies house. She does not appear to have any worries or fears about staying at my house from what I can tell. I just thought she would outgrow this by now but it seems to be getting worse instead of better.
Thanks
If the overnight aspect of the contact is causing her excessive distress, it would be reasonable to eliminate the overnight component and reinstate it later. This is definitely a judgement call, one which requires you to make a determination about the degree of upset and whether the cost/benefit balance rests one way or the other.