Hi Caran,
you suggest he meet you half way ... or you go to see him along with daughter and grandchildren. He's 70, he's not going to want to be bothered meeting you half way, has he mobility problems? You say he's embarrassed because his house is in a state, he's not going to want you visiting his house then, (especially) with other family members. Put yourself in his shoes, when's the last time he entertained anyone, in particular children in his home? Take your children out of the arrangement & meet him (his end) at a local cafe near to him. If he still isn't keen, there's nothing you can do. As long as he's o.k and has no major problems, all you can do is leave a contact address/ number to get in touch if ever he's in difficulty.