Edit: I see you said "physics engine". Updated my answer to reflect that and about your game...
Depends how the engine was written.
DBP cannot link object code so static objects are out. You can make calls to dlls, however this is limited and you'll see why in a moment. The following limits exist within DBP as apposed to C-alike languages:
DBP cannot pass any struct/array nor can it pass variables by ref.
DBP structs cannot contain arrays.
DBP has no pointer-to-functions, meaning no classes.
DBP's dynamic memory allocation is very limited.
DBP cannot use the address-of operator.
Short answer: Yes, but not without headache. Basically, you can only use your brother's engine if it can be compiled into a dll with functions requiring only basic data-types passed to / returned from them (there are hacks using raw memory but it is not relevant here unless you want that info).
FTR: There are physics add-ons for DBP.
Your game would have to be rewritten though, as BASIC and C are worlds apart, as are most of their derivs.
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