Each month that you have the child the gap will close and he will learn to play with the other kids. The crying when you leave the room is normal and that too will pass as he feels more comfortable with the group and the surroundings.

There are plenty of activities that they can do together. I have 13 months, 18 months and 19 months plus a 2 year old and a 3 year old. The younger three play blocks, still have a bin of baby toys they can take out and explore and several buckets to put stuff in and out of. The 13 month old and sometimes the 18 month old still have morning naps so during that time the 19 month old plays with the older two kids.

I wouldn't worry about the child not fitting in for play since at this age they still are pretty solitary in their activities so he will be fine if the others are doing their own thing.

Was the child coming from another care situation or are you also dealing with this being first time in care in which case we would allow a 12 month old longer to adjust. Six weeks is not abnormal before you see improvement. I would give it till end of June to see if you see a glimmer of hope or not.