From the Blondie website:
http://www.kingfeatures.com/features/comics/blondie/about.htm
"From flapper and playboy to pop culture icons. It was way back in 1930 when Dagwood Bumstead first met Blondie. (Consider yourself a true fan if you know Blondie’s maiden name.) "
OK, so what was Blondie’s maiden name? 
Boopadoop. She was a flapper with a well off husband, Dagwood, whose family thought she was too common for him. Eventually that aspect of the strip went by the wayside.
More from here:
Judging by Dagwood’s eagerness to start on the honeymoon, he was quite the horndog in his youth.
Betty Boop, Blondie’s half-sister, shortened the family name when she entered show business. 
Well lets face it - Blondie is a major babe! Although I always thought Daisy Mae was way more hot! (What was Lil’ Abner thinking?)
Sister of Betty Boop.
Is this true? Or was this just a question?
Blondie’s maiden name as revealed in the strip published on June 21st 1931 is Jinkers not Boopadoop. Someone has been mixing Betty Boop with Blondie.
Am I the only one who was going to say Harry?
Welcome to the SDMB, and thank you for that long overdue correction.
So, she’s not really B. Boopadoop? Ah!
Same thought I had!
Huh, so apparently Blondie’s family was at least well-off enough to have a live-in cook… Was the culture at the time such that that could still be considered “not well-off enough”?
What he said.
That, I’m not so sure about. Even the Saturday Evening Post article about Chic Young in 1948 gives her name as “Blondie Boop-boop-a-doop”.
The Dagwood and Blondie Man | The Saturday Evening Post (page 95, third column)
That strip that @cbird703 posted is a fascinating find. But it has no context.
Without any question at all, Blondie’s last name was Boopadoop. She was introduced that way and referred to in the strip that way. When the syndicate did publicity and put ads in newspapers, they referred to Blondie Boopadoop.
In August 1930, Blondie and Dagwood got engaged. Newspapers received a press release, like this one printed in the The Belleville [IL] News-Democrat.
Mr. and Mrs. J. Bolling Bumstead have the honor of announcing the engagement of their only son, Dagwood, to Miss Blondie Boopadoop, August Sixteenth, Nineteen Hundred Thirty.
When the Lebanon [PA] Daily News announced they were adding the Blondie comic strip on Oct. 8, 1930, the ad read “Blondie Boopadopp is a character whose life is one long laugh.” The San Francisco Examiner did the same on March 1, 1931, saying, “The female of the species is more deadly than the male. That’s Blondie Boopadoop…”
Every history of the comic strip in general (I have many) and every history of Blondie that I can find agrees that her maiden name was Boopadoop.
So who was Jinkers? He was pursuing Blondie’s mom! I don’t know why Blondie was at his home in that strip, but I know he wasn’t her father.
I also found the strip @Skywatcher ninja’d me with. But that indicates he not yet married to the mother, and that is what other sources say the relationship was.
I’ve been perusing Google’s newspaper archive for any clues but, so far, I’ve only found that runs early Blondie strips and they didn’t pick up the strip until a couple of years later.
I found the strip in newspapers.com and searched back and later a couple of months but the storyline wasn’t picked up. Oddly, putting Jinkers into their search doesn’t put up any hits. Apparently, the lettering in Blondie strips doesn’t get read by their OCR.
It’s fascinating to me that the Banks family from Mary Poppins is described in the book as not being rich despite the fact they had a maid and a governess.