Bil (DH brother) seperated from his wife about four years ago. They have two girls who are aged 10 and 11. Their seperation is ongoing and there has been issues between them regarding bil not paying maintenance and basically being a crap father, both myself and DH agree with this. After they split we had no contact with our nieces as BIL didn't want us getting involved. We know now its because he was not paying maintenance or visiting his daughters. We managed to get in contact with his ex wife and we got to see the girls and they had sleepovers in our home with our children. This happened regularly for six months. BIL was aware of this and began to make an effort to see them. His ex wife agreed to let their daughters stay with him overnight if he didn't drink alcohol or have anybody in the house. He did both, drank and had his on/off girlfriend stay. All of a sudden we had no contact with our nieces again. Of course we only found out the full story about a year later. We desperately miss them and would love to make contact but not sure how to go about it. I want to be respectful to my ex sil and also my nieces. Bil wants us to contact them but I'm not sure what's the best way to do this. We have continued to send birthday gifts, Christmas gifts etc but at the moment we have no phone number for my sil. DH thinks we should just call down to them but i don't think that's the right thing to do. Any advice welcome please.