Will and trust for two different countries

Note: I tried posting this in r/TillSverige but the mods deleted it for some reason. If anyone can suggest a more appropriate sub I’m all ears.

Our situation: Married retirees with adult children. Both dual citizens, USA and Sweden. Currently we are residing mainly in Sweden where we own property and a bank account; Sweden considers us residents. We last resided in the state of California where we also own property, have bank accounts, receive pension income and still pay taxes; we typically spend a couple months out of the year in California and California also considers us residents, at least for tax purposes.

We have had a will and trust as well as powers of attorney for our children to make financial and medical decision for us that were drawn up in California about a decade ago (and which probably need to be updated soon). At the time the will and trust were created we informed our USA attorney about our assets in Sweden. He told us these would be subject to the laws of inheritance in Sweden and would not be covered by our American will and trust.

Since we are spending most of our time in Sweden it occurred to us that we should also draw up a Swedish will and powers of attorney. A couple weeks ago we met with an attorney who initially offered us a flat rate for doing this. Our situation, other than having assets in two different countries, is relatively straightforward: for both countries we wish to inherit from each other when one of us dies and when both of us die we wish our estate to be split equally between our children (or their estates).

Yesterday our Swedish attorney contacted us and informed us that because of the existence of our will and trust in California, creating a Swedish will was going to be much more complicated and consequently much more expensive. This sounded odd to us which is why I am posting here.

My main question is this: Is it likely that what our Swedish attorney said is correct, that the presence of a will in one country affects a will written in another country? Frankly what our USA attorney told us, that separate wills are needed for separate countries, would appear to make more sense.

For the record I’ve also posted this in a sub for legal advice in California. If there really is an issue here then I’m happy to pay our Swedish attorney the money that is needed to avoid a hassle for our kids when we pass on, but at the same time I don’t want to get taken for an unnecessary financial ride.