>"I hope you understand that I do not expect you to write on Sunday if you like my plan. I shall consider silence as consent."

I think this is meant for the plan that JA suggested at the beginning of the letter;

"the present time would be favourable for Miss Sharpe's coming to us; it seems a more disengaged period with us than we are likely to have later in the summer. If Frank and Mary do come, it can hardly be before the middle of July, which will be allowing a reasonable length of visit for Miss Sharpe, supposing she begins it when you return; and if you and Martha do not dislike the plan, and she can avail herself of it, the opportunity of her being conveyed hither will be excellent.