Namely, DS and DD#2's bedrooms.
A couple of weeks ago SIL sent me a text asking for two colors for DS and DD#2's rooms. Being kind of busy I picked 2 colors each and messaged her back. Then she asked what color DD#2's room is, I said purple, she replied "perfect!" Now that I think about it, I think she is planning on ordering some kind of wall decals that DH's aunt recently started selling through Upper Case Living. With Christmas coming and DS's bday in October and DD's in January, I think she's looking at them for gifts. Aunt was passing out books at our annual camping weekend and I know everyone really got into them and started talking ideas, orders, etc. Me? Well.......
I'm not oppose to them entirely, I think they look very nice in other people's home. In ours? Just not our thing. Plus, I'm currently in the process of reorganizing their rooms and wall decor is something I like to pick out myself.
Without knowing for sure, how do I let her know we don't care for them? I'd hate for her to order them, pay for them and then find out we won't use them...even if it is a little nervy for her to assume we'd like her input on decor in our house.
Re: SIL and "decorations" for our house.....
Can you mention to her, you would like some input on it?
I was pretty much not into it either. I did buy something for DD's room and I have to say, I kinda fell for it and it's totally not my style. So, my advice would be to to try to keep an open mind on it.
Ugh, that sounds awful, lol...
I would say "hey remember you asked about the colors of the kids rooms? I'm thinking about ordering some of those decals from Aunt, is that what you were going to do? Because I'd love to take a closer look at the catalog!" And then if you don't like anything, just report back that "unfortunately, nothing in there really interested me".
Easy!
I disagree with the "easy" part- I would feel guilty even though there is no reason- but yes, exactly this is what you need to do.
I don't think it would be right to not say anything and then not use the product she ordered.
Mention casually, hey remember when you were asking me about the kids rooms, I realized I answered without thinking. We are probably going to be redecorating them soon, but I don't know what we're doing yet. I don't know what you're planning but I just wanted to give you a heads up.
It makes it sound like you're not thinking about the decals but that you've realized the information you gave her isn't going to be accurate much longer, but you don't know what you're changing them to yet. This may do the trick?
And yeah, I can't believe she is buying decals for their walls. It is a nice gesture, but seems pretty personal to pick out.
Thanks ladies!
I'm sure I'm just going to have to come out and message her...I need to ask her about a gift idea for niece anyway. She knows that we recently repainted DS's room as not long after he and DD#2 made a huge mess with the paint. I'm sure they'd be cute but I don't know where we'd put them and again, they're just not our style. I figure if I don't say something we'll be getting some from MIL as well. I just hate being put in this position....
DD#1~8/17/96------DS~10/24/05
I wouldn't like that either. I am very picky and want to pick out things for the kids' rooms myself. I am not a fan of decals either.
One time, SIL asked me what characters DD likes so she could get her bedding for her toddler bed for her birthday. I am not into the character/Disney/princess stuff at ALL. I can't remember what happened but I probably told her we already had one.
If you think maybe she didn't order them yet, you could casually mention that you are re-doing their rooms but haven't decided on themes for either of their rooms yet.
OR- just let them know you're picky
Everyone knows I'm really picky and actually ask if I'd like something specific- it might seem rude to some, but I do the same for them. I mean, would we all rather have things we like 
Love this response! I was thinking the same thing!