I just found out my sister is coming after almost a year and a half of not seeing each other... how do I welcome her?

With love and open arms :)
Other than that, I have no suggestions.

Maybe take her to childhood favorite places of you both.

Do something completely unlike you to freak her out. For example, tell her that you joined a sex cult.

I really wanted to give an Augustian like answer but she beat me to it above. A huge hug and “I missed you so much and I’m so happy to see you” is going to go a long way.

I’m with augustlan and Bluefreedom on this one as well. A bear style hug for a few seconds and some nice words is going to be awesome.

I haven’t seen my sister for 4 years now that I have no idea how could I welcome her if she’d ever come to my house! I think we wouldbjust hug each other very strong for a few moments, kisses and tears would probably me there for sure, it’ll be spontaneous I think! Good luck, I really envy you ;)

Aside from what’s mentioned above, have a few bouquets around of her favorite flowers, put a picture of her in the baby’s room, plan some activities that were rituals when you were kids, and have some classic comfort foods that you both remember, out on the table.

Also, try and plan some time for the two of you alone – hit a spa and indulge in a few beauty things together. Not only will you get a chance to catch up with her, but it also gives you the opportunity to reconnect.

With a hug.

I hardly ever see my sisters. They live thousands of miles away. When I do see them, I’m always filled with anxiety. Once you get that initial hug in, everything will flow from there. Enjoy the short time that you have, cook a special dinner and play a game together. Games can be very bonding.