How to stretch 2 pieces of salmon for 4 people?

TACOS!! Grab some corn tortillas, make some slaw and guacamole, maybe a couple of sides and you’re good to go!

This happens to me all the time! This is what I usually do:
We usually serve family style at home but it is great to plate the meal to make it look like smaller portions are intentional, like at a restaurant. So I may make risotto and sautéed vegetables as sides so I will artfully spoon the risotto onto the centre of the plate, stack the vegetables onto the risotto and top with the smaller portions of salmon. Here is the game changer: finish the plate like would be presented in a restaurant. Finely chopped herbs or an edible flower or two and a balsamic reduction squiggle on the salmon and your in laws won’t notice the portion difference. They will only feel pampered by the extra efforts that you have put into the meal. You could do the same with couscous, quinoa or potatoes.

Viet-style rice noodle bowls. This is how my mother stretched expensive protein for a family of 8. The bowls are composed of cooked rice vermicelli, topped with shredded lettuce, cucumbers, sprouts, and fresh herbs. Place a few ounces of cooked fish (we like grilled, but you can certainly bake or pan fry). Each person can customize his/her own bowl. Then dress with a sweet/spicy fish sauce vinaigrette. My favorite summer meal!

Improvise a fish chowder using your salmon, potatoes and corn (frozen will work). Serve with some nice bread, cornbread or biscuits.

If you have eggs, you could make a salmon omelet,
If you have eggs, milk and a pie crust, you could make a salmon quiche.

This salmon and chickpea dish is pretty hearty: https://food52.com/recipes/78633-slow-roasted-salmon-with-kale-chickpeas-fried-lemons You could increase the kale, decrease the amount of salmon to suit whatever you have, then maybe serve some bread alongside.