This purpose of multiple wives “Islaamically” was to protect and assist women. In those days, women did not work and were in danger should they set foot out of their houses (hence Hijaab). When widowed, women had no income and no ability to feed their family. So having a husband take on these women as second or third wives was truly a blessing. This is how it was MEANT to be (note there are many other scenarios such as wife 1 cannot conceive, wife 1 becomes too ill to serve the family etc etc). I’ve not seen these scenarios in practice, I’ve only seen horny old men who got a gal “in trouble” and married her, thus causing much heartache within the original family. Sorry, doesnt work unless it IS as it WAS INTENDED.
But be aware, it is illegal in the US. The first wife is “legal” and has rights if something should happen to the husband…she will be cared for and can legally inherit. A second wife has no legal rights whatsoever and would not be recognized as a family member. A “polygamist” in the US can end up in jail, thats the law here.