Now, as per lakehead email, If I want to accept the offer letter then I have to do before 27th March. But, I want to wait for ottawa response. If I accept lakehead offer then can I accept ottawa offer?
Well, kindly hold on till like March 25th before accepting. If you didn't get a response frok Ottawa by March 25th then you can accept. But when you get a response from Ottawa and it is positive then you can decline Lakehead by emailing thth you have changed your mind.
Let remain positive about your application to Ottawa.
All the best!