Thank you very much! Our account is joint but in the USA and we send a monthly stipend to her sister in discussion through (Transfer) Wise, which was suggested here. Fewer transfers would be better but my sister-in-law is poor at managing money. My wife does have a German account but we fund that at a low level to avoid tax filing obligations in the USA. But, we can and will designate transfers as Gift From ,,, messages in the future.
Many thanks!