I'm not oblivious to the suffering, jksijj and some others in the same situation have, I just dont have the answer. In church today, pastor was talking about not taking the lords name in vain, not really about cursing the name of the lord but not celebrating the name of the lord or giving him credit, as a LOONG in the TOOTH stepmom I know about how NOONE wants to say my name or even acknowledge my existence, even though I have been the long term WORKHORSE of the family. I spent the time in church today trying to figure out what is the name for the uptake at the end of a sentence that distinguishes between a period, an exclamation point or a question mark.  Its the tone of how we transfer meaning of a sentence to a person about what we are trying to say.   I don't know what I am talking about but you may.  there is a tone that as stepparents  may be able to use as a tool as a person married to or partnered with someone with kids that should learn or try to experiment with.  Me as a stepparent or grandstepparent will be condemned with whatever I say even though every other person in the family may be able to express themselves freely, If I say "how was your day?"  I am classified as being snotty and hateful or if I say "I see you got a new cat."  I am being hostile but if someone else says it they are not hostile, but its just because the people I try to communicate with dispute my existence in this room as opposed to MIL or an uncle saying the same sentence.  

Maybe you get what I'm talking about so I can try to explain the use of the comma in a sentence.  try this as an experiment, when  you speak or respond to a stepchild or an inlaw who is resentful of your existence, avoid the use of periods, explanation points and question marks in your sentence.  a period has a low tone, an explanation point has an expressive tone, and a question mark has an uptone, but practice a comma as an end to a sentence. its hard to explain, but there is a certain tone to a comma, waiting for the other part of the sentence to come, but practice that the second part never comes.  

example:   "You barfed on my shoes,"    

or "I put my sandwitch there for a second,"

or "you just called me bitch,"

or "you poked me in the eye,"

or "you took my chair when I got up,"

but don't finish the other part of the sentence and don't show any emotion. don't be mean, don't raise your voice, don't finish the sentence just keep on with what your doing, chose a different seat, make a second sandwitch, wear other shoes.  You let your spouse and stepkids and MIL and SIl know what they did and that you know what they did, but you didn't confront them, you didn't solve the problem for them, you called out what they did, but it was in a tone that was not challenging.  when you don't finish the sentence after the comma, it leaves them time to finish the sentence for themselves in their mind and solve the problem in their mind for themselves.  

"the clean towels were used to clean up dog poop,"

"you invited DH's ex wife that he hates to his birthday party,"

"You just called me the stepkids moms name,"

Learn the pitch of how a comma works in a sentence, its the medium pitch. its not the ending of a sentence its not a question and its not a statement.  Its the middle pitch, waiting for something else to come.... but it never comes and will drive them nuts..... waiting for the other shoe to fall, but it never does....because you are the wonderful one that your partner is so glad that they are with!!! You are there because its your spot. so try this because what do we have to lose, no one asked for us to be here anyway.