Words with multiple meanings

For words are spelt the same but have different meanings is it possible to add multiple definitions? What is the best way to deal with this situation in LingQ?

Yes, here’s how I do it in the web version. If you have a word selected and on the right it shows one hint that you’ve already chosen, clicking on “popular meanings” will show what other hints/definitions users have contributed. Select one of these if you want it, and it will show along with your original choice whenever the word is selected. If there are no additional definitions that you want, you can click on the “+” in the yellow circle to add one of your own, perhaps found in one of the available dictionaries. Whatever you enter will show alongside the first hint you’d selected. When hovering over any of your selected meanings there is an “X” in a red circle that can be used to remove it.
It’s also possible in the Android version. When viewing the first meaning you’ve added, touch “Deictionaries” or “Popular Translations”. Whatever you select or enter will be added as another meaning, not replacing the first. You can remove a meaning by swiping it to the right.
I don’t use any of the SRS tools, so I can’t say how/whether these employ multiple meanings that you’ve selected.

Edit: Some people will add multiple definitions in a single hint. You may have seen that. I’m not sure how I feel about that, especially if they’re not closely related, if at all.