// what is matter? never mind. 
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,avx2") 
#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
#define ll long long
#define int long long
#define ull unsigned long long
#define SZ(x) ((int)((x).size()))
#define ALL(x) (x).begin(),(x).end()
using namespace std;
inline int read()
{
    char c=getchar();int x=0;bool f=0;
    for(;!isdigit(c);c=getchar())f^=!(c^45);
    for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
    if(f)x=-x;return x;
}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;

#define maxn 505
#define inf 0x3f3f3f3f

int n,m;
char s[maxn][maxn];
int a[maxn][maxn];

void dfs(int x,int y){
	if(x<=0||y<=0||x>=n||y>=m)return;
	int s=a[x][y]+a[x+1][y]+a[x][y+1]+a[x+1][y+1];
	if(abs(s)==3){
		For(i,x,x+1) For(j,y,y+1) if(!a[i][j]){
			a[i][j]=-a[x+x+1-i][y+y+1-j];
			dfs(i,j);
			return;
		}
	}
}

void work()
{
	n=read(),m=read();
	For(i,1,n) cin>>(s[i]+1);
	For(i,1,n)For(j,1,n){
		if(s[i][j]=='?')a[i][j]=0;
		if(s[i][j]=='B')a[i][j]=1;
		if(s[i][j]=='W')a[i][j]=-1;
		if((i+j)%2)a[i][j]*=-1;
	}
	For(i,1,n-1)For(j,1,m-1)dfs(i,j);
	
	bool hav=0;
	For(x,1,n-1)For(y,1,m-1){
		int s=a[x][y]+a[x+1][y]+a[x][y+1]+a[x+1][y+1];
		if(abs(s)==4){
			puts("NO");
			return;
		}
	}
	
	For(i,1,n)
		For(j,1,m)
			if(!a[i][j]){
				a[i][j]=1;
				For(x,i-1,i)
					For(y,j-1,j)
						dfs(x,y);
			}
	puts("YES");
	For(i,1,n)
		For(j,1,m){
			if((i+j)%2)a[i][j]*=-1;
			if(a[i][j]==-1) cout<<"W";
			else cout<<"B";
			if(j==m)cout<<"\n";
		}
}

signed main()
{
	int T=read();
	while(T--)work();
	return 0;
}
/*
3
2 2
??
??
3 3
BW?
W?B
?BW
3 3
BW?
W?W
?W?
*/