Potty Training

Two female Dachshund's. Sisters. 7 months old. Use a leash outside and only one outside at a time. They want to play and explore instead of taking care of business. We do allow them to roam and play in the yard unleashed daily. We do our best to make sure we see them all the time. They are taken out on average of every 2 hours unless we are gone. They are almost never in their crate except at night or when we are gone.

We have pads in laundry room and house training is pretty good with an occasional accident-perhaps 1-2 times a week. No pee in over a month.

Problem we have is when 1st one is returned and the second one is out the first one will sometimes poop on a pad after she has been out. We watch them when eating near the back door and occasionally the more mature one will walk to the door and look at me. I take her out and sometimes she just sniffs everything and heads back to the house.

I need help on how to get them to alert us that she needs to go out. Also how do I get them to take care of business and not play when I take them out? They will roam and sniff until it is impossible to hold it any longer. Peeing is usually pretty quick.
It may take 20 minutes before they are through. That creates a problem when the weather is bad,

Since we got them almost 5 months ago they have slept in a kennel together at night without interruption. When in the house they are very active and don't sleep much.

I would think that at 7 months they would be house trained. Am I asking too much of them?