The MCL 2ABLI and MCL 2AV are both compatible with other MCL 2 equipment. However non of them will work as replacements for the MCL2 Expander as they do not have the circitry for amplifiying the data signal and supplying power to the MCL units after the expander. If you are not able to find a expander replacement you could look into alternative options depending on how many link rooms you have and how easy it is to do new cabling in your home. The BM5500 can be connected to Masterlink link room products with the addition of a Beolink Converter 1611 or 1612

Thank you, Madskp for pointing me in the right direction. I have four MCL 2A Type 2046 boxes connected to 7 speaker pairs. I just ordered a used MCL 2 Expander Type 2007 from Quality Dream Audio in the UK. Hopefully it will arrive in working order. I'll be on the lookout for one or two more of these devices as backups. It's good to know that the BM5500 can be connected with a Beolink Converter 1611 or 1612. I'll research these products in the event that I have to use this alternative solution. Again, thank you for taking time to help me.