when your step-mother is also your mother-in-law your kids only have 1 grandma

It's time for more fun with family history. This one is reminiscent of the old song I'm My Own Grandpa where the singer married a widow and his father married the widow's daughter, thus making him his own grandpa.

While working on a collateral line on my dad's side of the family, I came across an interesting situation. Someone even wrote a riddle about it and someone else posted it to ancestry.com. Alfred J. Cotton, the author, was married to Peter and Josiah's sister, Phebe.

Peter and Josiah's mother is my 4th great-aunt.

From "Cotton's Keepsake" by Rev. Judge Alfred J. Cotton.

Peter Platt to Susan N. Milliken.
Please tell me, you who know, (Those are excused who can't,)
How this man's brother is his uncle -- His brother's wife his aunt.
Still wilder pranks has Hymen played,  By the Union of these twain;
The Mother of this happy groom,  Is Mother to him again.

            ANSWER

Josiah Platt, "long time ago."

Married a fair damsel, even so, even so;

Then old Mr. Platt -- O what a twister!--

Soon afterward married his son's wife's sister;

And now gallant Peter not long did loiter,

Till he took for his spouse his step-mother's daughter;

So now, my young friends, I've 'splained the whole riddle,

If you can't understand it, you ain't worth a fiddle.

<<<<<<<<<<<<<<  EXPLANATION >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

The Riddle refers to the following Marriages: 

 Josiah Platt (1813-1858) to Mary Milliken (1818-1865) 23 Sep 1841.

 Peter Platt (1821-1903)  to Susan Milliken (1824-1875)  29 Oct 1842.

 (Peter is Josiah's Brother.  Mary is Susan's Aunt)

 Gilbert Platt (1772-1867) (3rd Mg) to the widow, Margaret Matthews Millikin (1791-1880) 8 Jun 1842. 

(Gilbert Platt is father to Peter and Josiah; Margaret is Susan's Mother)

When Gilbert marries Margaret, she is actually Mary Milliken's Sister-in-Law. (Sister by implication) 

SOOooo.. Margaret is already Peter's STEP-Mother when he marries Susan, she becomes his Mother-in-Law.