Supplementary food for puppy weight gain

[PerfectlyChaotic]

This is probably the opposite of most people's concerns, but my 18wk old puppy is a little on the lean side. She's had a massive growth spurt recently and I'm keen to know what I can add to her diet to help her fill out a little. She's fed a cold pressed dry food...it's v nutritionally dense. I've spoke to manufacturer & I'm definitely feeding enough for her weight - guidelines are to be super careful not to over feed (it goes straight through, so I know if I've overdone it!!). So what can I safely add for a reasonable sensitive tum? Sardines have been suggested... I wondered whether it's safe to add a little complete wet food. I've looked at the Lily's kitchen puppy dinner trays & wondered whether I could add a couple of spoonfuls once a day maybe? Is it ok to mix one complete with another 🙈 She also LOVES a stuffed Kong & it would be great to add a bit of extra good stuff this way maybe.... apologies for the essay, it's early & I'm in a muddle about what to do for the best!!

We had this when our dog was little - if we tried feeding more of his normal food it just went straight through him and all we had was more poo! We added a little wet food with his supper, gave him sardines a couple of times a week, scrambled egg, kongs stuffed with banana, yoghurt and kibble or chicken.

We'd been warned to watch his weight once he was neutered (when he'd finished growing) but that made no difference! He was a skinny minny until the last year or so when he started to put on more muscle. He's now 4 and still lean but looks strong and athletic so I think we've found a way of feeding him that works for him.

Our vet said some dogs are just calorie burners and ours is definitely so fizzy and energetic out on walks it's no surprise he burns through food so quickly

Just to add - it's much better for dogs to be on the lean side than a bit overweight. We tend to have a very skewed idea of what dogs should look like - they are supposed to be quite a bit leaner than most people think so we were quite often told our puppy was too thin by other dog walkers when actually he was on the lean side of ideal weight