Mixed themes?

Hello guys, thank you for your lovely themes.

I’m currently using Weta team, but i don’t like too much the portfolio feature that Jetpack has to displaying projects. Last year I bought Onigiri theme and I would like to know if I can use the Portfolio template of this theme in my Weta theme. Where do I have to do it? Directly to css editor? Do I have to ask for technical help?

Do you recommend buying another theme that could be more complete? I need portfolio – ecommerce and blog.

Thank you very much!