JQuery :: Replacing The Rows In A Table?

I have used jQ to replace table rows ok. For example,

Background [what works] A page with just js, html5, jQ, css: In the current page I view, I have a table id="Tbl1', with rows of the form

n=1,2,...
<tr id="Rn"> <td>...</td> <td>...</td> </tr>
var rid ='#R2';
var tr is anotherr row as above with n=2;
$(rid).replaceWith(tr); //will replace old row with new tr, matching the Rn. Good.

Also, I have another table id=Tbl2, in the same dom, but on a page that slides in and out using html5transition, on click. $('#Tbl2').append(tr); //works fine by appending to that Tbl2 (possiblyduplicatingrows)

[Problem] What is the exact syntax to do the $(rd).replaceWith(tr) operation on the contents of Tbl2. I have tried many combinations, but could not get it to work.

1. Looking for the syntax.

2. Incidiental question: Even though I have two tables, Tbl1, Tbl2, the first operation auto selects Tbl1 which appears second in the DOM after Tbl2.