My Fiance and I Have a Child, Can We Include Her Name on the Wedding Invitation?

Yes, and I’m sure she would love being included!

Assuming the two of you are hosting the wedding add her name under yours in the following manner:

John Jones and Jane Smith

together with their daughter Louise 

invite you to…

And since you are including her in the wedding invitation wording, you may also want to bring her with you to help pick out the wedding invitation.  I’m sure she’ll enjoy being part of the process.

You may want to take her to the cake tasting too.

I Want My Niece, She’s 3, to Be My Flower Girl But Not to Stay for the Reception. How Do I Tell My Sister?

You just have to tell her, but it’s your decision whether you want to be sincere or demanding in your approach.

I would suggest to her that they hire a sitter to come to the wedding and watch their daughter in another room or bring her back home so that your sister and her husband can have a great time at the reception.  Here you’re showing her that you’re thinking of her and not your wedding.

The other option is to be blunt and tell your sister you're planning an adult-only reception and that she must find sitter coverage for her daughter.

Since people are very sensitive when it comes to issues regarding their children I would  offer to help find them a sitter if they need assistance or even offer to pay for the coverage if you think money is the deciding factor.