Relative Pronoun Linking

I cannot figure out how to solve these questions. My frustrations has reached a level where I am blaming the computer, since everything needs to be correct.(punctuation, capital letters, etc.) And the computer does not tell you what is wrong with the sentence. Help me please?

There are 20 questions and to pass I need 14 correct ones. I currently have 13 and cannot figure out the last one!

LINK THE FOLLOWING SENTENCES, USING A NON-DEFINING RELATIVE PRONOUN (WHO, WHOSE, WHICH). Example: We cannot maintain this machine any longer. We bought it two years ago. Answer: We cannot maintain this machine, which we bought two years ago, any longer..
WRITE THE FULL SENTENCE, NOT JUST THE RELATIVE PRONOUN

Sentences I need to change.

1. The singer had to cancel her concert. She was recovering from flu.
2. I'm afraid we can't relax our payment terms. Our payment terms are not that strict anyway.
3. Our company’s liquidity problems are being resolved. The problems were caused by the high dollar rate.
4. The Finance Manager was forced to step down. He had not succeeded in reducing the company’s losses.
5. The newspaper is owned by the Mears Group. The chairperson of the Mears Group is Sir James Bex.
6. I don’t see my father very often. He lives in Barbados.
   

My changed sentences that the computer says is wrong.

1. The singer, who was recovering from the flu, had to cancel her concert.
2. The Finance Manager, who had not succeeded in reducing the company’s losses, was forced to step down.
3. I'm afraid we can't, whose payment terms are not that strict anyway, relax our payment terms.
4. I don’t see my father, who lives in Barbados, very often.
5. Our company’s liquidity problems, which were caused by the high dollar rate, are being resolved.
6. The newspaper, which chairperson of the Mears Group is Sir James Bex, is owned by the Mears Group.

Thank you so much!