It's extremely hard on a relationship/marriage when you have a MiniWife involved. Ask me how I know. I remember in our early days of our relationship, DH and I were reading a book together on marriage. His daughter found out, started reading the book and wanted to discuss it with him. I was appalled. And I expressed that to DH in clear terms. Thankfully, he noticed the improper inmeshment (it goes DEEP in that family of orgin because of the BM) and made changes. I can say this and mean it...we'd have never made it had he not made changes. I'm not competing with any woman in my marriage, including a MiniWife. 

She has inserted herself over the years but I address it right when it happens...like the time DH and I made a decision on something and she did her best to sway him to her (and his other kids opinion). Didn't happen. She still caused discourse in our marriage for years but we stood strong....coming up to 19 years together. These days, she's quiet. Or DH has learned how to manage her without me knowing. Who knows??

I'm hoping your SO/DH sees the damage this is doing to your relationship...coffee time is a good start. Best to you.

Of course he does. Because he makes a lot more effort to connect with her than he does to you, his wife. Technology is part of the problem - they can reach out to each other with the tap of a finger. 

As you noted, their relationship was like this before you married. I don't mean this disrespectfully, but why did you think it would change when you married? Did you have a serious discussion with him prior, and he just lapsed back into this behavior?  

If he said he would change things when you married, and hasn't, then you have a platform to stand on. I do know that there are many people who are constantly communicating with others in their families.  I have friends who do this - texting their grown kids several times a day (often every few hours!), sending photos, etc. It's obsessive and controlling, IMO. That's probably because I come from a generation where you had to actually go to a phone, dial it and if the person wasn't at home you were just out of luck. (Didn't even have answering machines back then!)  We all got along, lived our lives.

Ask your DH if he can use the old "phone on the kitchen wall" as a guidepost for awhile. Only contact SD once a day, briefly, as though he were standing at the phone. Maybe do a brief call in the morning, but ensuring he is free to have morning coffee with you. Then he pledges to NOT communicate with her throughout the rest of the day. 

Added: FWIW, Pew Research did a study recently and found that 19% of fathers text their adult children daily. So use some statistics on your DH - he is WAY out of the norm if he is texting multiple times per day. 

I like the idea (and 2Tired's suggestion) of you having uninterrupted coffee with your husband in the morning--and if his phone dings or rings, ask him if he can take the text or call later, when you two aren't in each other's company. You say that you have no relationship with his daughter. I think it's interesting that he has included you in some group texts. I think you should start engaging in those texts. If his daughter doesn't like you, that may inspire her to back off. I think it's interesting that he takes photos when he's out with you and sends them to his daughters. My husband has never done that because the skids and I have pretty  much erased one another. So, it looks like your husband wants to include you (maybe too much). Seems to me that this will be a slow process of you two establishing some boundaries (he shouldn't share everything you say to him with his daughter--that needs to stop!) while re-engaging with one another. 

You can set up uninterrupted coffee time at 6:30 am to 7;30. No phone calls no texts.  Good way to start the morning. SD is trying to control DH. Is a game for her.  You must take an active role,  you must inform DH, Since SD is disrespectful to you, Ge will have your back. As in no calling or texting SD in your presence.  As going out, to the store, movies. Dinner, ect.  You must let DH know he too old to be playing her game.  It's his choice, your rules or go live with SD.  

I went through a similar hell. Miniwives are really hard on a marriage. Inserting herself in everything, big and small. Interrupting dates and travel for Dadddeeee's attention.  I finally had it. He could pick one wife, but he couldn't have both.

Took him a while, but she no longer runs his life. They've gone from constants texts/calls to her not speaking with him at all. She's upset with him but won't tell him why.

Be very clear with your DH that there is room for only two people in your marriage.

Creepy AF

Ive been you. Its NOT RIGHT period.

Obviously you have been mini wifed and he just expects you to wait in the sidelines, cause this works for big daddio.

Hun I know I say this often on here. I can only go by what I read. Only you know this in entirety but IMHO  please RUN. You are in a sister daughter wife relationship. Those rarely work out.

It crushes your soul, crushes your dignity , crushes your self esteem.

Blessings 

it sounds like codependancy on steroids. Have you asked him why he feels the need to communicate with her on that level? Have you told him how you feel about or how 'not normal' their relationship is? How long have you been married? I apologize if you've addressed all this in the thread already.

This is pretty creepy.  Good luck.

I have been married to a DH of five children for three decades. My relationship with his children as adults has been mostly unpleasant. I allowed myself to be mistreated, and once I began setting boundaries, my life changed for the better. I won't allow them or anyone to mistreat me. I don't see three of his adult children because they treat me poorly.