I need 3 issues resolving in Xero and then some on going support

My mother in law has been looking after Xero but she is terminally ill. I need someone to look after us ongoing - just check everything is OK once per month on two small businesses. On one of the businesses some existing assets were not entered as conversion balances and Im struggling too do it. I have tried but they do not appear on the balance sheet or asset list so I have clearly screwed up. I also have a sales invoice which flags up as not balancing when I try to enter a conversion balance