Coupled return is for married or common-law people or widowed-in-tax-year only. Coupled return means two returns in one file. An un-coupled return file is one file one return; Coupled return can exchange spouse income and credit claim information for both tax payer automatically; otherwise uncoupled return file requires you to enter spouse info manually.
There is no advantage of using uncoupled return for a couple; if uncoupled return is done properly, it will have same result as coupled return.
In newer version of myTaxExpress you can switch between returns by clicking on the "Switch tax return by selecting name" drop down list. Then click on the name of the person whose return you want to switch to.
On older version of the software, you can switch tax return to your spouse's by the list box labelled as "tax return for", under the title bar. By finishing both of your tax return, spousal tax information are updated in each other's tax return automatically.